procps 010114
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csmall
437
sysctl.c
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437
sysctl.c
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/*
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* Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
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*
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*
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* "Copyright 1999 George Staikos
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* This file may be used subject to the terms and conditions of the
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* GNU General Public License Version 2, or any later version
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* at your option, as published by the Free Software Foundation.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details."
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*
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* Changelog:
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* v1.01:
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* - added -p <preload> to preload values from a file
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <dirent.h>
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#include <string.h>
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#include <errno.h>
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/*
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* Additional types we might need.
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*/
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typedef int bool;
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static bool true = 1;
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static bool false = 0;
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/*
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* Function Prototypes
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*/
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int Usage(const char *name);
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void Preload(const char *filename);
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int WriteSetting(const char *setting);
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int ReadSetting(const char *setting);
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int DisplayAll(const char *path, bool ShowTableUtil);
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/*
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* Globals...
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*/
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const char *PROC_PATH = "/proc/sys/";
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const char *DEFAULT_PRELOAD = "/etc/sysctl.conf";
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static bool PrintName;
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static bool PrintNewline;
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/* error messages */
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const char *ERR_UNKNOWN_PARAMETER = "error: Unknown parameter '%s'\n";
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const char *ERR_MALFORMED_SETTING = "error: Malformed setting '%s'\n";
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const char *ERR_NO_EQUALS = "error: '%s' must be of the form name=value\n";
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const char *ERR_INVALID_KEY = "error: '%s' is an unknown key\n";
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const char *ERR_UNKNOWN_WRITING = "error: unknown error %d setting key '%s'\n";
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const char *ERR_UNKNOWN_READING = "error: unknown error %d reading key '%s'\n";
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const char *ERR_PERMISSION_DENIED = "error: permission denied on key '%s'\n";
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const char *ERR_OPENING_DIR = "error: unable to open directory '%s'\n";
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const char *ERR_PRELOAD_FILE = "error: unable to open preload file '%s'\n";
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const char *WARN_BAD_LINE = "warning: %s(%d): invalid syntax, continuing...\n";
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#define DOTSLASH(x) do{ \
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char *p_ = (x); \
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for(;;){ \
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p_ = strchr(p_, '.'); \
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if(!p_) break; \
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*p_ = '/'; \
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} \
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}while(0)
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#define SLASHDOT(x) do{ \
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char *p_ = (x); \
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for(;;){ \
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p_ = strchr(p_, '.'); \
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if(!p_) break; \
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*p_ = '/'; \
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} \
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}while(0)
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/*
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* Main...
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*
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*/
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int main(int argc, char **argv) {
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const char *me = (const char *)basename(argv[0]);
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bool SwitchesAllowed = true;
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bool WriteMode = false;
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int ReturnCode = 0;
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const char *preloadfile = DEFAULT_PRELOAD;
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PrintName = true;
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PrintNewline = true;
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if (argc < 2) {
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return Usage(me);
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} /* endif */
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argv++;
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for (; argv && *argv && **argv; argv++) {
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if (SwitchesAllowed && **argv == '-') { /* we have a switch */
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switch((*argv)[1]) {
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case 'b':
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/* This is "binary" format, which means more for BSD. */
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PrintNewline = false;
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/* FALL THROUGH */
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case 'n':
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PrintName = false;
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break;
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case 'w':
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SwitchesAllowed = false;
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WriteMode = true;
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break;
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case 'p':
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argv++;
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if (argv && *argv && **argv) {
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preloadfile = *argv;
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} /* endif */
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Preload(preloadfile);
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return(0);
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break;
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case 'a': /* string and integer values (for Linux, all of them) */
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case 'A': /* the above, including "opaques" (would be unprintable) */
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case 'X': /* the above, with opaques completly printed in hex */
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SwitchesAllowed = false;
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return DisplayAll(PROC_PATH, ((*argv)[1] == 'a') ? false : true);
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case 'h':
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case '?':
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return Usage(me);
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default:
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fprintf(stderr, ERR_UNKNOWN_PARAMETER, *argv);
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return Usage(me);
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} /* end switch */
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} else {
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SwitchesAllowed = false;
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if (WriteMode)
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ReturnCode = WriteSetting(*argv);
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else ReadSetting(*argv);
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} /* end if */
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} /* end for */
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return ReturnCode;
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} /* end main */
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/*
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* Display the usage format
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*
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*/
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int Usage(const char *name) {
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printf("usage: %s [-n] variable ... \n"
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" %s [-n] -w variable=value ... \n"
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" %s [-n] -a \n"
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" %s [-n] -p <file> (default /etc/sysctl.conf) \n"
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" %s [-n] -A\n", name, name, name, name, name);
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return -1;
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} /* end Usage() */
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/*
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* Strip the leading and trailing spaces from a string
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*
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*/
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char *StripLeadingAndTrailingSpaces(char *oneline) {
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char *t;
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if (!oneline || !*oneline)
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return oneline;
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t = oneline;
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t += strlen(oneline)-1;
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while ((*t == ' ' || *t == '\t' || *t == '\n' || *t == '\r') && t != oneline)
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*t-- = 0;
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t = oneline;
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while ((*t == ' ' || *t == '\t') && *t != 0)
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t++;
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return t;
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} /* end StripLeadingAndTrailingSpaces() */
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/*
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* Preload the sysctl's from the conf file
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* - we parse the file and then reform it (strip out whitespace)
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*
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*/
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void Preload(const char *filename) {
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FILE *fp;
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char oneline[257];
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char buffer[257];
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char *t;
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int n = 0;
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char *name, *value;
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if (!filename || ((fp = fopen(filename, "r")) == NULL)) {
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fprintf(stderr, ERR_PRELOAD_FILE, filename);
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return;
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} /* endif */
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while (fgets(oneline, 256, fp)) {
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oneline[256] = 0;
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n++;
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t = StripLeadingAndTrailingSpaces(oneline);
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if (strlen(t) < 2)
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continue;
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if (*t == '#' || *t == ';')
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continue;
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name = strtok(t, "=");
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if (!name || !*name) {
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fprintf(stderr, WARN_BAD_LINE, filename, n);
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continue;
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} /* endif */
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StripLeadingAndTrailingSpaces(name);
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value = strtok(NULL, "\n\r");
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if (!value || !*value) {
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fprintf(stderr, WARN_BAD_LINE, filename, n);
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continue;
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} /* endif */
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while ((*value == ' ' || *value == '\t') && *value != 0)
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value++;
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sprintf(buffer, "%s=%s", name, value);
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WriteSetting(buffer);
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} /* endwhile */
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fclose(fp);
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} /* end Preload() */
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/*
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* Write a sysctl setting
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*
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*/
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int WriteSetting(const char *setting) {
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int rc = 0;
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const char *name = setting;
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const char *value;
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const char *equals;
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char *tmpname;
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FILE *fp;
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char *outname;
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if (!name) { /* probably dont' want to display this err */
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return 0;
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} /* end if */
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equals = index(setting, '=');
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if (!equals) {
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fprintf(stderr, ERR_NO_EQUALS, setting);
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return -1;
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} /* end if */
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value = equals + sizeof(char); /* point to the value in name=value */
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if (!*name || !*value || name == equals) {
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fprintf(stderr, ERR_MALFORMED_SETTING, setting);
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return -2;
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} /* end if */
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tmpname = (char *)malloc((equals-name+1+strlen(PROC_PATH))*sizeof(char));
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outname = (char *)malloc((equals-name+1)*sizeof(char));
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strcpy(tmpname, PROC_PATH);
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strncat(tmpname, name, (int)(equals-name));
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tmpname[equals-name+strlen(PROC_PATH)] = 0;
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strncpy(outname, name, (int)(equals-name));
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outname[equals-name] = 0;
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DOTSLASH(tmpname); /* change . to / */
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SLASHDOT(outname); /* change / to . */
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fp = fopen(tmpname, "w");
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if (!fp) {
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switch(errno) {
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case ENOENT:
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fprintf(stderr, ERR_INVALID_KEY, outname);
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break;
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case EACCES:
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fprintf(stderr, ERR_PERMISSION_DENIED, outname);
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break;
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default:
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fprintf(stderr, ERR_UNKNOWN_WRITING, errno, outname);
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break;
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} /* end switch */
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rc = -1;
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} else {
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fprintf(fp, "%s\n", value);
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fclose(fp);
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if (PrintName) {
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fprintf(stdout, "%s = %s\n", outname, value);
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} else {
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if (PrintNewline)
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fprintf(stdout, "%s\n", value);
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else
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fprintf(stdout, "%s", value);
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}
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} /* endif */
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free(tmpname);
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free(outname);
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return rc;
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} /* end WriteSetting() */
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/*
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* Read a sysctl setting
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*
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*/
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int ReadSetting(const char *setting) {
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int rc = 0;
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char *tmpname, *outname;
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char inbuf[1025];
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const char *name = setting;
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FILE *fp;
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if (!setting || !*setting) {
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fprintf(stderr, ERR_INVALID_KEY, setting);
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} /* endif */
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tmpname = (char *)malloc((strlen(name)+strlen(PROC_PATH)+1)*sizeof(char));
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outname = (char *)malloc((strlen(name)+1)*sizeof(char));
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strcpy(tmpname, PROC_PATH);
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strcat(tmpname, name);
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strcpy(outname, name);
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DOTSLASH(tmpname); /* change . to / */
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SLASHDOT(outname); /* change / to . */
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fp = fopen(tmpname, "r");
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if (!fp) {
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switch(errno) {
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case ENOENT:
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fprintf(stderr, ERR_INVALID_KEY, outname);
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break;
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case EACCES:
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fprintf(stderr, ERR_PERMISSION_DENIED, outname);
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break;
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default:
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fprintf(stderr, ERR_UNKNOWN_READING, errno, outname);
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break;
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} /* end switch */
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rc = -1;
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} else {
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while(fgets(inbuf, 1024, fp)) {
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/* already has the \n in it */
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if (PrintName) {
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fprintf(stdout, "%s = %s", outname, inbuf);
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} else {
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if (!PrintNewline) {
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char *nlptr = strchr(inbuf,'\n');
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if(nlptr) *nlptr='\0';
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}
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fprintf(stdout, "%s", inbuf);
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}
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} /* endwhile */
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fclose(fp);
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} /* endif */
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free(tmpname);
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free(outname);
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return rc;
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} /* end ReadSetting() */
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/*
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* Display all the sysctl settings
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*
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*/
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int DisplayAll(const char *path, bool ShowTableUtil) {
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int rc = 0;
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int rc2;
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DIR *dp;
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struct dirent *de;
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char *tmpdir;
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struct stat ts;
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dp = opendir(path);
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if (!dp) {
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fprintf(stderr, ERR_OPENING_DIR, path);
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rc = -1;
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} else {
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readdir(dp); readdir(dp); /* skip . and .. */
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while (( de = readdir(dp) )) {
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tmpdir = (char *)malloc(strlen(path)+strlen(de->d_name)+2);
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sprintf(tmpdir, "%s%s", path, de->d_name);
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rc2 = stat(tmpdir, &ts); /* should check this return code */
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if (rc2 != 0) {
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perror(tmpdir);
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} else {
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if (S_ISDIR(ts.st_mode)) {
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strcat(tmpdir, "/");
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DisplayAll(tmpdir, ShowTableUtil);
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} else {
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rc |= ReadSetting(tmpdir+strlen(PROC_PATH));
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} /* endif */
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} /* endif */
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free(tmpdir);
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} /* end while */
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closedir(dp);
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} /* endif */
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return rc;
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} /* end DisplayAll() */
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