Minor documentation updates.

[coloredstderr/coloredstderr.git] / src / coloredstderr.c

diff --git a/src/coloredstderr.c b/src/coloredstderr.c
index b16633f8534b8b7d9a1e4fdc64532a185497c598..a55ce38d15fd67dcc3abcc787f3cf6a1de608003 100644 (file)
--- a/src/coloredstderr.c
+++ b/src/coloredstderr.c
@@ -77,7 +77,7 @@ static int check_handle_fd(int fd) {
 
 static void dup_fd(int oldfd, int newfd) {
 #ifdef DEBUG
-    debug("%d -> %d\t\t\t[%d]\n", oldfd, newfd, getpid());
+    debug("%3d -> %3d\t\t\t[%d]\n", oldfd, newfd, getpid());
 #endif
 
     if (!initialized) {
@@ -105,7 +105,7 @@ static void dup_fd(int oldfd, int newfd) {
 
 static void close_fd(int fd) {
 #ifdef DEBUG
-    debug("%d -> .\t\t\t[%d]\n", fd, getpid());
+    debug("%3d ->   .\t\t\t[%d]\n", fd, getpid());
 #endif
 
     if (!initialized) {
@@ -206,7 +206,7 @@ HOOK_FILE2(int, vprintf, stdout,
            const char *, format, va_list, ap)
 HOOK_FILE3(int, vfprintf, stream,
            FILE *, stream, const char *, format, va_list, ap)
-/* Hardening functions (-D_FORTIFY_SOURCE=2). */
+/* Hardening functions (-D_FORTIFY_SOURCE=2), only functions from above */
 HOOK_VAR_FILE2(int, __printf_chk, stdout, __vprintf_chk,
                int, flag, const char *, format)
 HOOK_VAR_FILE3(int, __fprintf_chk, fp, __vfprintf_chk,
@@ -302,6 +302,7 @@ int fcntl(int fd, int cmd, ...) {
     va_start(ap, cmd);
     result = real_fcntl(fd, cmd, va_arg(ap, void *));
     va_end(ap);
+
     /* We only care about duping fds. */
     if (cmd == F_DUPFD && result != -1) {
         int saved_errno = errno;
@@ -326,3 +327,23 @@ int fclose(FILE *fp) {
     close_fd(fileno(fp));
     return real_fclose(fp);
 }
+
+
+/* Hook functions which are necessary for correct tracking. */
+
+#if defined(HAVE_VFORK) && defined(HAVE_FORK)
+pid_t vfork(void) {
+    /* vfork() is similar to fork() but the address space is shared between
+     * father and child. It's designed for fork()/exec() usage because it's
+     * faster than fork(). However according to the POSIX standard the "child"
+     * isn't allowed to perform any memory-modifications before the exec()
+     * (except the pid_t result variable of vfork()).
+     *
+     * As some programs don't adhere to the standard (e.g. the "child" closes
+     * or dups a descriptor before the exec()) and this breaks our tracking of
+     * file descriptors (e.g. it gets closed in the parent as well), we just
+     * fork() instead. This is in compliance with the POSIX standard and as
+     * most systems use copy-on-write anyway not a performance issue. */
+    return fork();
+}
+#endif