busybox/libbb/xfuncs.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 * Copyright (C) 2006 Rob Landley
 * Copyright (C) 2006 Denis Vlasenko
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "busybox.h"

/* All the functions starting with "x" call bb_error_msg_and_die() if they
 * fail, so callers never need to check for errors.  If it returned, it
 * succeeded. */

#ifndef DMALLOC
/* dmalloc provides variants of these that do abort() on failure.
 * Since dmalloc's prototypes overwrite the impls here as they are
 * included after these prototypes in libbb.h, all is well.
 */
#ifdef L_xmalloc
/* Die if we can't allocate size bytes of memory. */
void *xmalloc(size_t size)
{
	void *ptr = malloc(size);
	if (ptr == NULL && size != 0)
		bb_error_msg_and_die(bb_msg_memory_exhausted);
	return ptr;
}
#endif

#ifdef L_xrealloc
/* Die if we can't resize previously allocated memory.  (This returns a pointer
 * to the new memory, which may or may not be the same as the old memory.
 * It'll copy the contents to a new chunk and free the old one if necessary.) */
void *xrealloc(void *ptr, size_t size)
{
	ptr = realloc(ptr, size);
	if (ptr == NULL && size != 0)
		bb_error_msg_and_die(bb_msg_memory_exhausted);
	return ptr;
}
#endif
#endif /* DMALLOC */


#ifdef L_xzalloc
/* Die if we can't allocate and zero size bytes of memory. */
void *xzalloc(size_t size)
{
	void *ptr = xmalloc(size);
	memset(ptr, 0, size);
	return ptr;
}
#endif

#ifdef L_xstrdup
/* Die if we can't copy a string to freshly allocated memory. */
char * xstrdup(const char *s)
{
	char *t;

	if (s == NULL)
		return NULL;

	t = strdup (s);

	if (t == NULL)
		bb_error_msg_and_die(bb_msg_memory_exhausted);

	return t;
}
#endif

#ifdef L_xstrndup
/* Die if we can't allocate n+1 bytes (space for the null terminator) and copy
 * the (possibly truncated to length n) string into it.
 */
char * xstrndup(const char *s, int n)
{
	char *t;

	if (ENABLE_DEBUG && s == NULL)
		bb_error_msg_and_die("xstrndup bug");

	t = xmalloc(++n);

	return safe_strncpy(t,s,n);
}
#endif

#ifdef L_xfopen
/* Die if we can't open a file and return a FILE * to it.
 * Notice we haven't got xfread(), This is for use with fscanf() and friends.
 */
FILE *xfopen(const char *path, const char *mode)
{
	FILE *fp;
	if ((fp = fopen(path, mode)) == NULL)
		bb_perror_msg_and_die("%s", path);
	return fp;
}
#endif

#ifdef L_xopen
/* Die if we can't open an existing file and return an fd. */
int xopen(const char *pathname, int flags)
{
	if (ENABLE_DEBUG && (flags & O_CREAT))
		bb_error_msg_and_die("xopen() with O_CREAT");

	return xopen3(pathname, flags, 0777);
}
#endif

#ifdef L_xopen3
/* Die if we can't open a new file and return an fd. */
int xopen3(const char *pathname, int flags, int mode)
{
	int ret;

	ret = open(pathname, flags, mode);
	if (ret < 0) {
		bb_perror_msg_and_die("%s", pathname);
	}
	return ret;
}
#endif

#ifdef L_xread
/* Die with an error message if we can't read the entire buffer. */
void xread(int fd, void *buf, size_t count)
{
	while (count) {
		ssize_t size;

		if ((size = safe_read(fd, buf, count)) < 1)
			bb_error_msg_and_die("Short read");
		count -= size;
		buf = ((char *) buf) + size;
	}
}
#endif

#ifdef L_xwrite
/* Die with an error message if we can't write the entire buffer. */
void xwrite(int fd, void *buf, size_t count)
{
	while (count) {
		ssize_t size;

		if ((size = safe_write(fd, buf, count)) < 1)
			bb_error_msg_and_die("Short write");
		count -= size;
		buf = ((char *) buf) + size;
	}
}
#endif

#ifdef L_xlseek
/* Die with an error message if we can't lseek to the right spot. */
void xlseek(int fd, off_t offset, int whence)
{
	if (offset != lseek(fd, offset, whence)) bb_error_msg_and_die("lseek");
}
#endif

#ifdef L_xread_char
/* Die with an error message if we can't read one character. */
unsigned char xread_char(int fd)
{
	char tmp;

	xread(fd, &tmp, 1);

	return(tmp);
}
#endif

#ifdef L_xferror
/* Die with supplied error message if this FILE * has ferror set. */
void xferror(FILE *fp, const char *fn)
{
	if (ferror(fp)) {
		bb_error_msg_and_die("%s", fn);
	}
}
#endif

#ifdef L_xferror_stdout
/* Die with an error message if stdout has ferror set. */
void xferror_stdout(void)
{
	xferror(stdout, bb_msg_standard_output);
}
#endif

#ifdef L_xfflush_stdout
/* Die with an error message if we have trouble flushing stdout. */
void xfflush_stdout(void)
{
	if (fflush(stdout)) {
		bb_perror_msg_and_die(bb_msg_standard_output);
	}
}
#endif

#ifdef L_spawn
/* This does a fork/exec in one call, using vfork().  Return PID of new child,
 * -1 for failure.  Runs argv[0], searching path if that has no / in it.
 */
pid_t spawn(char **argv)
{
	static int failed;
	pid_t pid;
	void *app = ENABLE_FEATURE_SH_STANDALONE_SHELL ? find_applet_by_name(argv[0]) : 0;

	/* Be nice to nommu machines. */
	failed = 0;
	pid = vfork();
	if (pid < 0) return pid;
	if (!pid) {
		execvp(app ? CONFIG_BUSYBOX_EXEC_PATH : *argv, argv);

		/* We're sharing a stack with blocked parent, let parent know we failed
		 * and then exit to unblock parent (but don't run atexit() stuff, which
		   would screw up parent.) */

		failed = -1;
		_exit(0);
	}
	return failed ? failed : pid;
}
#endif

#ifdef L_xspawn
/* Die with an error message if we can't spawn a child process. */
pid_t xspawn(char **argv)
{
	pid_t pid = spawn(argv);
	if (pid < 0) bb_perror_msg_and_die("%s", *argv);
	return pid;
}
#endif

#ifdef L_wait4
/* Wait for the specified child PID to exit, returning child's error return. */
int wait4pid(int pid)
{
	int status;

	if (pid == -1 || waitpid(pid, &status, 0) == -1) return -1;
	if (WIFEXITED(status)) return WEXITSTATUS(status);
	if (WIFSIGNALED(status)) return WTERMSIG(status);
	return 0;
}
#endif

#ifdef L_itoa
/* Convert unsigned integer to ascii, writing into supplied buffer.  A
 * truncated result is always null terminated (unless buflen is 0), and
 * contains the first few digits of the result ala strncpy. */
void utoa_to_buf(unsigned n, char *buf, unsigned buflen)
{
	int i, out = 0;
	if (buflen) {
		for (i=1000000000; i; i/=10) {
			int res = n/i;

			if ((res || out || i == 1) && --buflen>0) {
				out++;
				n -= res*i;
				*buf++ = '0' + res;
			}
		}
		*buf = 0;
	}
}

/* Convert signed integer to ascii, like utoa_to_buf() */
void itoa_to_buf(int n, char *buf, unsigned buflen)
{
	if (buflen && n<0) {
		n = -n;
		*buf++ = '-';
		buflen--;
	}
	utoa_to_buf((unsigned)n, buf, buflen);
}

/* The following two functions use a static buffer, so calling either one a
 * second time will overwrite previous results.
 *
 * The largest 32 bit integer is -2 billion plus null terminator, or 12 bytes.
 * Int should always be 32 bits on any remotely Unix-like system, see
 * http://www.unix.org/whitepapers/64bit.html for the reasons why.
*/
static char local_buf[12];

/* Convert unsigned integer to ascii using a static buffer (returned). */
char *utoa(unsigned n)
{
	utoa_to_buf(n, local_buf, sizeof(local_buf));

	return local_buf;
}

/* Convert signed integer to ascii using a static buffer (returned). */
char *itoa(int n)
{
	itoa_to_buf(n, local_buf, sizeof(local_buf));

	return local_buf;
}
#endif

#ifdef L_setuid
/* Die with an error message if we can't set gid.  (Because resource limits may
 * limit this user to a given number of processes, and if that fills up the
 * setgid() will fail and we'll _still_be_root_, which is bad.) */
void xsetgid(gid_t gid)
{
	if (setgid(gid)) bb_error_msg_and_die("setgid");
}

/* Die with an error message if we cant' set uid.  (See xsetgid() for why.) */
void xsetuid(uid_t uid)
{
	if (setuid(uid)) bb_error_msg_and_die("setuid");
}
#endif

#ifdef L_fdlength
/* Return how long the file at fd is, if there's any way to determine it. */
off_t fdlength(int fd)
{
	off_t bottom = 0, top = 0, pos;
	long size;

	/* If the ioctl works for this, return it. */

	if (ioctl(fd, BLKGETSIZE, &size) >= 0) return size*512;

	/* If not, do a binary search for the last location we can read.  (Some
	 * block devices don't do BLKGETSIZE right.) */

	do {
		char temp;

		pos = bottom + (top - bottom) / 2;

		/* If we can read from the current location, it's bigger. */

		if (lseek(fd, pos, 0)>=0 && safe_read(fd, &temp, 1)==1) {
			if (bottom == top) bottom = top = (top+1) * 2;
			else bottom = pos;

		/* If we can't, it's smaller. */

		} else {
			if (bottom == top) {
				if (!top) return 0;
				bottom = top/2;
			}
			else top = pos;
		}
	} while (bottom + 1 != top);

	return pos + 1;
}
#endif

#ifdef L_xasprintf
/* Die with an error message if we can't malloc() enough space and do an
 * sprintf() into that space. */
char *xasprintf(const char *format, ...)
{
	va_list p;
	int r;
	char *string_ptr;

#if 1
	// GNU extension
	va_start(p, format);
	r = vasprintf(&string_ptr, format, p);
	va_end(p);
#else
	// Bloat for systems that haven't got the GNU extension.
	va_start(p, format);
	r = vsnprintf(NULL, 0, format, p);
	va_end(p);
	string_ptr = xmalloc(r+1);
	va_start(p, format);
	r = vsnprintf(string_ptr, r+1, format, p);
	va_end(p);
#endif

	if (r < 0) bb_error_msg_and_die(bb_msg_memory_exhausted);
	return string_ptr;
}
#endif

#ifdef L_xprint_and_close_file
/* Die with an error message if we can't copy an entire FILE * to stdout, then
 * close that file. */
void xprint_and_close_file(FILE *file)
{
	// copyfd outputs error messages for us.
	if (bb_copyfd_eof(fileno(file), 1) == -1)
		exit(bb_default_error_retval);

	fclose(file);
}
#endif

#ifdef L_xchdir
/* Die if we can't chdir to a new path. */
void xchdir(const char *path)
{
	if (chdir(path))
		bb_perror_msg_and_die("chdir(%s)", path);
}
#endif

#ifdef L_warn_opendir
/* Print a warning message if opendir() fails, but don't die. */
DIR *warn_opendir(const char *path)
{
	DIR *dp;

	if ((dp = opendir(path)) == NULL) {
		bb_perror_msg("unable to open `%s'", path);
		return NULL;
	}
	return dp;
}
#endif

#ifdef L_xopendir
/* Die with an error message if opendir() fails. */
DIR *xopendir(const char *path)
{
	DIR *dp;

	if ((dp = opendir(path)) == NULL)
		bb_perror_msg_and_die("unable to open `%s'", path);
	return dp;
}
#endif

#ifdef L_xdaemon
#ifndef BB_NOMMU
/* Die with an error message if we can't daemonize. */
void xdaemon(int nochdir, int noclose)
{
	if (daemon(nochdir, noclose)) bb_perror_msg_and_die("daemon");
}
#endif
#endif

#ifdef L_xsocket
/* Die with an error message if we can't open a new socket. */
int xsocket(int domain, int type, int protocol)
{
	int r = socket(domain, type, protocol);

	if (r < 0) bb_perror_msg_and_die("socket");

	return r;
}
#endif

#ifdef L_xbind
/* Die with an error message if we can't bind a socket to an address. */
void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen)
{
	if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind");
}
#endif

#ifdef L_xlisten
/* Die with an error message if we can't listen for connections on a socket. */
void xlisten(int s, int backlog)
{
	if (listen(s, backlog)) bb_perror_msg_and_die("listen");
}
#endif

#ifdef L_xstat
/* xstat() - a stat() which dies on failure with meaningful error message */
void xstat(char *name, struct stat *stat_buf)
{
        if (stat(name, stat_buf))
                bb_perror_msg_and_die("Can't stat '%s'", name);
}
#endif