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echo: do not retry on write errors

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function                                             old     new   delta
echo_main                                            297     336     +39
stpcpy                                                 -      22     +22
run_pipe                                            1561    1566      +5
pseudo_exec_argv                                     187     192      +5
hush_exit                                             75      80      +5
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(add/remove: 3/0 grow/shrink: 4/0 up/down: 98/0)               Total: 76 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2011-02-07 02:03:51 +01:00
parent b8ab4b0388
commit 8ee2adab21
7 changed files with 74 additions and 40 deletions
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87
coreutils/echo.c
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@@ -29,46 +29,42 @@
/* NB: can be used by shell even if not enabled as applet */
/*
* NB2: we don't use stdio, we need better error handing.
* Examples include writing into non-opened stdout and error on write.
*
* With stdio, output gets shoveled into stdout buffer, and even
* fflush cannot clear it out. It seems that even if libc receives
* EBADF on write attempts, it feels determined to output data no matter what.
* If echo is called by shell, it will try writing again later, and possibly
* will clobber future output. Not good.
*
* Solaris has fpurge which discards buffered input. glibc has __fpurge.
* But this function is not standard.
*/
int echo_main(int argc UNUSED_PARAM, char **argv)
{
char **pp;
const char *arg;
char *out;
char *buffer;
unsigned buflen;
int r;
#if !ENABLE_FEATURE_FANCY_ECHO
enum {
eflag = '\\',
nflag = 1, /* 1 -- print '\n' */
};
/* We must check that stdout is not closed.
* The reason for this is highly non-obvious.
* echo_main is used from shell. Shell must correctly handle "echo foo"
* if stdout is closed. With stdio, output gets shoveled into
* stdout buffer, and even fflush cannot clear it out. It seems that
* even if libc receives EBADF on write attempts, it feels determined
* to output data no matter what. So it will try later,
* and possibly will clobber future output. Not good. */
// TODO: check fcntl() & O_ACCMODE == O_WRONLY or O_RDWR?
if (fcntl(1, F_GETFL) == -1)
return 1; /* match coreutils 6.10 (sans error msg to stderr) */
//if (dup2(1, 1) != 1) - old way
// return 1;
arg = *++argv;
if (!arg)
goto newline_ret;
argv++;
#else
const char *p;
char nflag = 1;
char eflag = 0;
/* We must check that stdout is not closed. */
if (fcntl(1, F_GETFL) == -1)
return 1;
while (1) {
arg = *++argv;
if (!arg)
goto newline_ret;
if (*arg != '-')
while ((arg = *++argv) != NULL) {
if (!arg || arg[0] != '-')
break;
/* If it appears that we are handling options, then make sure
@@ -77,7 +73,7 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
*/
p = arg + 1;
if (!*p) /* A single '-', so echo it. */
goto just_echo;
break;
do {
if (!strrchr("neE", *p))
@@ -95,19 +91,27 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
}
just_echo:
#endif
while (1) {
/* arg is already == *argv and isn't NULL */
buflen = 1;
pp = argv;
while ((arg = *pp) != NULL) {
buflen += strlen(arg) + 1;
pp++;
}
out = buffer = xmalloc(buflen);
while ((arg = *argv) != NULL) {
int c;
if (!eflag) {
/* optimization for very common case */
fputs(arg, stdout);
out = stpcpy(out, arg);
} else while ((c = *arg++)) {
if (c == eflag) { /* Check for escape seq. */
if (*arg == 'c') {
/* '\c' means cancel newline and
* ignore all subsequent chars. */
goto ret;
goto do_write;
}
#if !ENABLE_FEATURE_FANCY_ECHO
/* SUSv3 specifies that octal escapes must begin with '0'. */
@@ -127,21 +131,26 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
c = bb_process_escape_sequence(&arg);
}
}
bb_putchar(c);
*out++ = c;
}
arg = *++argv;
if (!arg)
if (!*++argv)
break;
bb_putchar(' ');
*out++ = ' ';
}
newline_ret:
if (nflag) {
bb_putchar('\n');
*out++ = '\n';
}
ret:
return fflush_all();
do_write:
r = full_write(STDOUT_FILENO, buffer, out - buffer);
free(buffer);
if (r < 0) {
bb_perror_msg(bb_msg_write_error);
return 1;
}
return 0;
}
/*-