Merge branch 'js/exec-error-report'

* js/exec-error-report:
Improve error message when a transport helper was not found
start_command: detect execvp failures early
run-command: move wait_or_whine earlier
start_command: report child process setup errors to the parent's stderr

Conflicts:
Makefile

diff --git a/Makefile b/Makefile
index d74c1962340597f2f4afc760f09c3b1bd764b4f0..cf0723ea122b09c66a6da367a653381966729847 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1778,6 +1778,7 @@ TEST_PROGRAMS_NEED_X += test-genrandom
 TEST_PROGRAMS_NEED_X += test-match-trees
 TEST_PROGRAMS_NEED_X += test-parse-options
 TEST_PROGRAMS_NEED_X += test-path-utils
+TEST_PROGRAMS_NEED_X += test-run-command
 TEST_PROGRAMS_NEED_X += test-sha1
 TEST_PROGRAMS_NEED_X += test-sigchain
 TEST_PROGRAMS_NEED_X += test-index-version

diff --git a/run-command.c b/run-command.c
index a90984576411d237c1b83b66427e99d9e37ea7c8..2feb493951322617692085998ac8507cdba9dd30 100644 (file)
--- a/run-command.c
+++ b/run-command.c
@@ -61,6 +61,78 @@ static int execv_shell_cmd(const char **argv)
 }
 #endif
 
+#ifndef WIN32
+static int child_err = 2;
+static int child_notifier = -1;
+
+static void notify_parent(void)
+{
+       write(child_notifier, "", 1);
+}
+
+static NORETURN void die_child(const char *err, va_list params)
+{
+       char msg[4096];
+       int len = vsnprintf(msg, sizeof(msg), err, params);
+       if (len > sizeof(msg))
+               len = sizeof(msg);
+
+       write(child_err, "fatal: ", 7);
+       write(child_err, msg, len);
+       write(child_err, "\n", 1);
+       exit(128);
+}
+
+static inline void set_cloexec(int fd)
+{
+       int flags = fcntl(fd, F_GETFD);
+       if (flags >= 0)
+               fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+}
+#endif
+
+static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
+{
+       int status, code = -1;
+       pid_t waiting;
+       int failed_errno = 0;
+
+       while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
+               ;       /* nothing */
+
+       if (waiting < 0) {
+               failed_errno = errno;
+               error("waitpid for %s failed: %s", argv0, strerror(errno));
+       } else if (waiting != pid) {
+               error("waitpid is confused (%s)", argv0);
+       } else if (WIFSIGNALED(status)) {
+               code = WTERMSIG(status);
+               error("%s died of signal %d", argv0, code);
+               /*
+                * This return value is chosen so that code & 0xff
+                * mimics the exit code that a POSIX shell would report for
+                * a program that died from this signal.
+                */
+               code -= 128;
+       } else if (WIFEXITED(status)) {
+               code = WEXITSTATUS(status);
+               /*
+                * Convert special exit code when execvp failed.
+                */
+               if (code == 127) {
+                       code = -1;
+                       failed_errno = ENOENT;
+                       if (!silent_exec_failure)
+                               error("cannot run %s: %s", argv0,
+                                       strerror(ENOENT));
+               }
+       } else {
+               error("waitpid is confused (%s)", argv0);
+       }
+       errno = failed_errno;
+       return code;
+}
+
 int start_command(struct child_process *cmd)
 {
        int need_in, need_out, need_err;
@@ -122,9 +194,30 @@ int start_command(struct child_process *cmd)
        trace_argv_printf(cmd->argv, "trace: run_command:");
 
 #ifndef WIN32
+{
+       int notify_pipe[2];
+       if (pipe(notify_pipe))
+               notify_pipe[0] = notify_pipe[1] = -1;
+
        fflush(NULL);
        cmd->pid = fork();
        if (!cmd->pid) {
+               /*
+                * Redirect the channel to write syscall error messages to
+                * before redirecting the process's stderr so that all die()
+                * in subsequent call paths use the parent's stderr.
+                */
+               if (cmd->no_stderr || need_err) {
+                       child_err = dup(2);
+                       set_cloexec(child_err);
+               }
+               set_die_routine(die_child);
+
+               close(notify_pipe[0]);
+               set_cloexec(notify_pipe[1]);
+               child_notifier = notify_pipe[1];
+               atexit(notify_parent);
+
                if (cmd->no_stdin)
                        dup_devnull(0);
                else if (need_in) {
@@ -165,8 +258,16 @@ int start_command(struct child_process *cmd)
                                        unsetenv(*cmd->env);
                        }
                }
-               if (cmd->preexec_cb)
+               if (cmd->preexec_cb) {
+                       /*
+                        * We cannot predict what the pre-exec callback does.
+                        * Forgo parent notification.
+                        */
+                       close(child_notifier);
+                       child_notifier = -1;
+
                        cmd->preexec_cb();
+               }
                if (cmd->git_cmd) {
                        execv_git_cmd(cmd->argv);
                } else if (cmd->use_shell) {
@@ -174,13 +275,39 @@ int start_command(struct child_process *cmd)
                } else {
                        execvp(cmd->argv[0], (char *const*) cmd->argv);
                }
-               trace_printf("trace: exec '%s' failed: %s\n", cmd->argv[0],
-                               strerror(errno));
-               exit(127);
+               /*
+                * Do not check for cmd->silent_exec_failure; the parent
+                * process will check it when it sees this exit code.
+                */
+               if (errno == ENOENT)
+                       exit(127);
+               else
+                       die_errno("cannot exec '%s'", cmd->argv[0]);
        }
        if (cmd->pid < 0)
                error("cannot fork() for %s: %s", cmd->argv[0],
                        strerror(failed_errno = errno));
+
+       /*
+        * Wait for child's execvp. If the execvp succeeds (or if fork()
+        * failed), EOF is seen immediately by the parent. Otherwise, the
+        * child process sends a single byte.
+        * Note that use of this infrastructure is completely advisory,
+        * therefore, we keep error checks minimal.
+        */
+       close(notify_pipe[1]);
+       if (read(notify_pipe[0], &notify_pipe[1], 1) == 1) {
+               /*
+                * At this point we know that fork() succeeded, but execvp()
+                * failed. Errors have been reported to our stderr.
+                */
+               wait_or_whine(cmd->pid, cmd->argv[0],
+                             cmd->silent_exec_failure);
+               failed_errno = errno;
+               cmd->pid = -1;
+       }
+       close(notify_pipe[0]);
+}
 #else
 {
        int fhin = 0, fhout = 1, fherr = 2;
@@ -271,48 +398,6 @@ int start_command(struct child_process *cmd)
        return 0;
 }
 
-static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
-{
-       int status, code = -1;
-       pid_t waiting;
-       int failed_errno = 0;
-
-       while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
-               ;       /* nothing */
-
-       if (waiting < 0) {
-               failed_errno = errno;
-               error("waitpid for %s failed: %s", argv0, strerror(errno));
-       } else if (waiting != pid) {
-               error("waitpid is confused (%s)", argv0);
-       } else if (WIFSIGNALED(status)) {
-               code = WTERMSIG(status);
-               error("%s died of signal %d", argv0, code);
-               /*
-                * This return value is chosen so that code & 0xff
-                * mimics the exit code that a POSIX shell would report for
-                * a program that died from this signal.
-                */
-               code -= 128;
-       } else if (WIFEXITED(status)) {
-               code = WEXITSTATUS(status);
-               /*
-                * Convert special exit code when execvp failed.
-                */
-               if (code == 127) {
-                       code = -1;
-                       failed_errno = ENOENT;
-                       if (!silent_exec_failure)
-                               error("cannot run %s: %s", argv0,
-                                       strerror(ENOENT));
-               }
-       } else {
-               error("waitpid is confused (%s)", argv0);
-       }
-       errno = failed_errno;
-       return code;
-}
-
 int finish_command(struct child_process *cmd)
 {
        return wait_or_whine(cmd->pid, cmd->argv[0], cmd->silent_exec_failure);

diff --git a/t/t0061-run-command.sh b/t/t0061-run-command.sh
new file mode 100755 (executable)
index 0000000..10b26e4
--- /dev/null
+++ b/t/t0061-run-command.sh
@@ -0,0 +1,14 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Ilari Liusvaara
+#
+
+test_description='Test run command'
+
+. ./test-lib.sh
+
+test_expect_success 'start_command reports ENOENT' '
+       test-run-command start-command-ENOENT ./does-not-exist
+'
+
+test_done

diff --git a/test-run-command.c b/test-run-command.c
new file mode 100644 (file)
index 0000000..0612bfa
--- /dev/null
+++ b/test-run-command.c
@@ -0,0 +1,35 @@
+/*
+ * test-run-command.c: test run command API.
+ *
+ * (C) 2009 Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
+ *
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "git-compat-util.h"
+#include "run-command.h"
+#include <string.h>
+#include <errno.h>
+
+int main(int argc, char **argv)
+{
+       struct child_process proc;
+
+       memset(&proc, 0, sizeof(proc));
+
+       if (argc < 3)
+               return 1;
+       proc.argv = (const char **)argv+2;
+
+       if (!strcmp(argv[1], "start-command-ENOENT")) {
+               if (start_command(&proc) < 0 && errno == ENOENT)
+                       return 0;
+               fprintf(stderr, "FAIL %s\n", argv[1]);
+               return 1;
+       }
+
+       fprintf(stderr, "check usage\n");
+       return 1;
+}

diff --git a/transport-helper.c b/transport-helper.c
index fdf22562201d12d1321baae9157a0ca70053a7cb..107742891f6e68d4b103f61a425a585770b0d155 100644 (file)
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -102,6 +102,7 @@ static struct child_process *get_helper(struct transport *transport)
        int refspec_nr = 0;
        int refspec_alloc = 0;
        int duped;
+       int code;
 
        if (data->helper)
                return data->helper;
@@ -111,13 +112,18 @@ static struct child_process *get_helper(struct transport *transport)
        helper->out = -1;
        helper->err = 0;
        helper->argv = xcalloc(4, sizeof(*helper->argv));
-       strbuf_addf(&buf, "remote-%s", data->name);
+       strbuf_addf(&buf, "git-remote-%s", data->name);
        helper->argv[0] = strbuf_detach(&buf, NULL);
        helper->argv[1] = transport->remote->name;
        helper->argv[2] = remove_ext_force(transport->url);
-       helper->git_cmd = 1;
-       if (start_command(helper))
-               die("Unable to run helper: git %s", helper->argv[0]);
+       helper->git_cmd = 0;
+       helper->silent_exec_failure = 1;
+       code = start_command(helper);
+       if (code < 0 && errno == ENOENT)
+               die("Unable to find remote helper for '%s'", data->name);
+       else if (code != 0)
+               exit(code);
+
        data->helper = helper;
        data->no_disconnect_req = 0;