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Make strace_popen abort on error

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It makes no sense to postpone abort on strace_popen error
unti it returns. Moreover, out-of-memory error was exiting
without any message.
While at it, use 0 as "none" for popen_pid, as optimization.

* strace: Initialize popen_pid to 0 - this puts it in bss.
  (trace): Reset popen_pid to 0 instead of -1.
  (strace_popen): Never return NULL as error indicator,
  abort with good error message instead.
  (main): Remove NULL check of strace_popen result.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2011-06-22 13:03:56 +02:00
parent 2b60c35b33
commit 7dd23384f7
1 changed files with 26 additions and 50 deletions
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74
strace.c
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@ -354,7 +354,7 @@ strace_fopen(const char *path, const char *mode)
return fp;
}
static int popen_pid = -1;
static int popen_pid = 0;
#ifndef _PATH_BSHELL
# define _PATH_BSHELL "/bin/sh"
@ -368,56 +368,38 @@ static int popen_pid = -1;
static FILE *
strace_popen(const char *command)
{
FILE *fp;
int fds[2];
swap_uid();
if (pipe(fds) < 0)
{
fprintf(stderr, "%s: pipe: %s\n",
progname, strerror(errno));
swap_uid();
return NULL;
}
perror_msg_and_die("pipe");
if (set_cloexec_flag(fds[1]) < 0)
{
close(fds[0]);
set_cloexec_flag(fds[1]); /* never fails */
popen_pid = vfork();
if (popen_pid == -1)
perror_msg_and_die("vfork");
if (popen_pid == 0) {
/* child */
close(fds[1]);
swap_uid();
return NULL;
}
if ((popen_pid = fork()) == -1)
{
fprintf(stderr, "%s: fork: %s\n",
progname, strerror(errno));
if (fds[0] != 0) {
if (dup2(fds[0], 0))
perror_msg_and_die("dup2");
close(fds[0]);
close(fds[1]);
swap_uid();
return NULL;
}
execl(_PATH_BSHELL, "sh", "-c", command, NULL);
perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL);
}
if (popen_pid)
{
/* parent */
close(fds[0]);
swap_uid();
return fdopen(fds[1], "w");
} else
{
/* child */
close(fds[1]);
if (fds[0] && (dup2(fds[0], 0) || close(fds[0])))
{
fprintf(stderr, "%s: dup2: %s\n",
progname, strerror(errno));
_exit(1);
}
execl(_PATH_BSHELL, "sh", "-c", command, NULL);
fprintf(stderr, "%s: execl: %s: %s\n",
progname, _PATH_BSHELL, strerror(errno));
_exit(1);
}
fp = fdopen(fds[1], "w");
if (!fp)
error_msg_and_die("Out of memory");
return fp;
}
static int
@ -1150,15 +1132,9 @@ main(int argc, char *argv[])
* We can't do the <outfname>.PID funny business
* when using popen, so prohibit it.
*/
if (followfork > 1) {
fprintf(stderr, "\
%s: piping the output and -ff are mutually exclusive options\n",
progname);
exit(1);
}
if ((outf = strace_popen(outfname + 1)) == NULL)
exit(1);
if (followfork > 1)
error_msg_and_die("Piping the output and -ff are mutually exclusive");
outf = strace_popen(outfname + 1);
}
else if (followfork <= 1 &&
(outf = strace_fopen(outfname, "w")) == NULL)
@ -2509,7 +2485,7 @@ trace()
}
if (pid == popen_pid) {
if (WIFEXITED(status) || WIFSIGNALED(status))
popen_pid = -1;
popen_pid = 0;
continue;
}
if (debug)