Merge branch 'jk/maint-1.6.1-cleanup-after-exec-failure' into maint-1.6.1

* jk/maint-1.6.1-cleanup-after-exec-failure:
  git: use run_command() to execute dashed externals
  run_command(): help callers distinguish errors
  run_command(): handle missing command errors more gracefully
  git: s/run_command/run_builtin/

git.c

@@ -2,6 +2,7 @@
 #include "exec_cmd.h"
 #include "cache.h"
 #include "quote.h"
+#include "run-command.h"
 
 const char git_usage_string[] =
 	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";
@@ -219,7 +220,7 @@ struct cmd_struct {
 	int option;
 };
 
-static int run_command(struct cmd_struct *p, int argc, const char **argv)
+static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
 {
 	int status;
 	struct stat st;
@@ -384,7 +385,7 @@ static void handle_internal_command(int argc, const char **argv)
 		struct cmd_struct *p = commands+i;
 		if (strcmp(p->cmd, cmd))
 			continue;
-		exit(run_command(p, argc, argv));
+		exit(run_builtin(p, argc, argv));
 	}
 }
 
@@ -392,6 +393,7 @@ static void execv_dashed_external(const char **argv)
 {
 	struct strbuf cmd = STRBUF_INIT;
 	const char *tmp;
+	int status;
 
 	strbuf_addf(&cmd, "git-%s", argv[0]);
 
@@ -406,10 +408,17 @@ static void execv_dashed_external(const char **argv)
 
 	trace_argv_printf(argv, "trace: exec:");
 
-	/* execvp() can only ever return if it fails */
-	execvp(cmd.buf, (char **)argv);
-
-	trace_printf("trace: exec failed: %s\n", strerror(errno));
+	/*
+	 * if we fail because the command is not found, it is
+	 * OK to return. Otherwise, we just pass along the status code.
+	 */
+	status = run_command_v_opt(argv, 0);
+	if (status != -ERR_RUN_COMMAND_EXEC) {
+		if (IS_RUN_COMMAND_ERR(status))
+			die("unable to run '%s'", argv[0]);
+		exit(-status);
+	}
+	errno = ENOENT; /* as if we called execvp */
 
 	argv[0] = tmp;
 

run-command.c

@@ -118,7 +118,9 @@ int start_command(struct child_process *cmd)
 		} else {
 			execvp(cmd->argv[0], (char *const*) cmd->argv);
 		}
-		die("exec %s failed.", cmd->argv[0]);
+		trace_printf("trace: exec '%s' failed: %s\n", cmd->argv[0],
+				strerror(errno));
+		exit(127);
 	}
 #else
 	int s0 = -1, s1 = -1, s2 = -1;	/* backups of stdin, stdout, stderr */
@@ -187,6 +189,7 @@ int start_command(struct child_process *cmd)
 #endif
 
 	if (cmd->pid < 0) {
+		int err = errno;
 		if (need_in)
 			close_pair(fdin);
 		else if (cmd->in)
@@ -197,7 +200,9 @@ int start_command(struct child_process *cmd)
 			close(cmd->out);
 		if (need_err)
 			close_pair(fderr);
-		return -ERR_RUN_COMMAND_FORK;
+		return err == ENOENT ?
+			-ERR_RUN_COMMAND_EXEC :
+			-ERR_RUN_COMMAND_FORK;
 	}
 
 	if (need_in)
@@ -236,9 +241,14 @@ static int wait_or_whine(pid_t pid)
 		if (!WIFEXITED(status))
 			return -ERR_RUN_COMMAND_WAITPID_NOEXIT;
 		code = WEXITSTATUS(status);
-		if (code)
+		switch (code) {
+		case 127:
+			return -ERR_RUN_COMMAND_EXEC;
+		case 0:
+			return 0;
+		default:
 			return -code;
-		return 0;
+		}
 	}
 }
 

run-command.h

@@ -10,6 +10,7 @@ enum {
 	ERR_RUN_COMMAND_WAITPID_SIGNAL,
 	ERR_RUN_COMMAND_WAITPID_NOEXIT,
 };
+#define IS_RUN_COMMAND_ERR(x) ((x) <= -ERR_RUN_COMMAND_FORK)
 
 struct child_process {
 	const char **argv;