Make strace_popen abort on error

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>

diff --git a/strace.c b/strace.c
index 84fc1b77bb050d69e94b47d91ce177224ef145a6..4c91e51984895ce99decfdfe8e4359ae28e8a33e 100644 (file)
--- a/strace.c
+++ b/strace.c
@@ -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)
 {
-       int     fds[2];
+       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]);
-               close(fds[1]);
-               swap_uid();
-               return NULL;
-       }
+       set_cloexec_flag(fds[1]); /* never fails */
 
-       if ((popen_pid = fork()) == -1)
-       {
-               fprintf(stderr, "%s: fork: %s\n",
-                       progname, strerror(errno));
-               close(fds[0]);
-               close(fds[1]);
-               swap_uid();
-               return NULL;
-       }
+       popen_pid = vfork();
+       if (popen_pid == -1)
+               perror_msg_and_die("vfork");
 
-       if (popen_pid)
-       {
-               /* parent */
-               close(fds[0]);
-               swap_uid();
-               return fdopen(fds[1], "w");
-       } else
-       {
+       if (popen_pid == 0) {
                /* 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);
+               if (fds[0] != 0) {
+                       if (dup2(fds[0], 0))
+                               perror_msg_and_die("dup2");
+                       close(fds[0]);
                }
                execl(_PATH_BSHELL, "sh", "-c", command, NULL);
-               fprintf(stderr, "%s: execl: %s: %s\n",
-                       progname, _PATH_BSHELL, strerror(errno));
-               _exit(1);
+               perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL);
        }
+
+       /* parent */
+       close(fds[0]);
+       swap_uid();
+       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)