Re: [PATCH v5 5/6] bisect--helper: reimplement `bisect_run` shell function in C

Hi Johannes,


El mar, 24 ago 2021 a las 15:59, Johannes Schindelin
([off-list ref]) escribió:

Hi Miriam,

On Fri, 20 Aug 2021, Miriam Rubio wrote:

quoted

From: Tanushree Tumane <redacted>

Reimplement the `bisect_run()` shell function
in C and also add `--bisect-run` subcommand to
`git bisect--helper` to call it from git-bisect.sh.

Mentored-by: Christian Couder [off-list ref]
Signed-off-by: Tanushree Tumane <redacted>
Signed-off-by: Miriam Rubio <redacted>
---
 builtin/bisect--helper.c | 102 +++++++++++++++++++++++++++++++++++++++
 git-bisect.sh            |  62 +-----------------------
 2 files changed, 103 insertions(+), 61 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 1e118a966a..8d33c809aa 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c

@@ -18,6 +18,7 @@ static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
 static GIT_PATH_FUNC(git_path_head_name, "head-name")
 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
 static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
+static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")

 static const char * const git_bisect_helper_usage[] = {
      N_("git bisect--helper --bisect-reset [<commit>]"),

@@ -31,6 +32,7 @@ static const char * const git_bisect_helper_usage[] = {
      N_("git bisect--helper --bisect-replay <filename>"),
      N_("git bisect--helper --bisect-skip [(<rev>|<range>)...]"),
      N_("git bisect--helper --bisect-visualize"),
+     N_("git bisect--helper --bisect-run <cmd>..."),
      NULL
 };

@@ -144,6 +146,25 @@ static int append_to_file(const char *path, const char *format, ...)
      return res;
 }

+static int print_file_to_stdout(const char *path)
+{
+     FILE *fp;
+     char c;
+
+     fp = fopen(path, "r");
+     if (!fp)
+             return error_errno(_("cannot open file '%s' in read mode"), path);
+
+     c = fgetc(fp);
+     while (c != EOF) {
+             printf ("%c", c);
+             c = fgetc(fp);
+     }
+
+     fclose(fp);

Rather than reading byte for byte (even if buffered), how about using
`copy_fd()`? Something like

        int fd = open(path, O_RDONLY), ret = 0;

        if (fd < 0)
                return error_errno(_("cannot open file '%s' for reading"), path);
        if (copy_fd(fd, 1) < 0)
                ret = error_errno(_("failed to read '%s'"), path);
        close(fd);
        return ret;

Ok. Noted.

quoted

+     return 0;
+}
+
 static int check_term_format(const char *term, const char *orig_term)
 {
      int res;

@@ -1075,6 +1096,78 @@ static int bisect_visualize(struct bisect_terms *terms, const char **argv, int a
      return res;
 }

+static int bisect_run(struct bisect_terms *terms, const char **argv, int argc)
+{
+     int res = BISECT_OK;
+     struct strbuf command = STRBUF_INIT;
+     struct strvec args = STRVEC_INIT;
+     struct strvec run_args = STRVEC_INIT;
+     const char *new_state;
+     int temporary_stdout_fd, saved_stdout;
+
+     if (bisect_next_check(terms, NULL))
+             return BISECT_FAILED;
+
+     if (argc)
+             sq_quote_argv(&command, argv);
+     else {
+             error(_("bisect run failed: no command provided."));
+             return BISECT_FAILED;
+     }
+
+     strvec_push(&run_args, command.buf);
+
+     while (1) {
+             strvec_clear(&args);
+
+             printf(_("running %s\n"), command.buf);
+             res = run_command_v_opt(run_args.v, RUN_USING_SHELL);
+
+             if (res < 0 || 128 <= res) {
+                     error(_("bisect run failed: exit code %d from"
+                             " '%s' is < 0 or >= 128"), res, command.buf);
+                     strbuf_release(&command);
+                     return res;
+             }
+
+             if (res == 125)
+                     new_state = "skip";
+             else new_state = res > 0 ? terms->term_bad : terms->term_good;

I do not care _all_ that much about formatting, but I think others on this
list do, and might point out that the `else` wants to live on its own
line.

Ok. I'll change that.

quoted

+             temporary_stdout_fd = open(git_path_bisect_run(), O_CREAT | O_WRONLY | O_TRUNC, 0666);
+             saved_stdout = dup(1);
+             dup2(temporary_stdout_fd, 1);

This temporary redirection looks a bit iffy. I wonder whether there is a
way to tell `bisect_state()` to print to a given file descriptor, _in
addition to_ `stdout`? That would also make `print_file_to_stdout()`
obsolete.

What calls exactly are making that print to `stdout` anyway?

I was trying to recreate the cat command with this solution as it is
in the shell script, without changing behavior or parameters in other
functions.
I think the most important prints to stdout come from
bisect_next_all() in bisect.c. The sequence is bisect_state()
->bisect_auto_next() ->  bisect_next() ->bisect_next_all().
Just to clarify: if we add a file descriptor as parameter in
bisect_state(), we have to propagate it to a lot of functions, is that
what we want?

This is my only remaining issue with the current 5/6.

Thank you for reviewing!
Miriam

Thank you,
Dscho

quoted

+
+             res = bisect_state(terms, &new_state, 1);
+
+             dup2(saved_stdout, 1);
+             close(saved_stdout);
+             close(temporary_stdout_fd);
+
+             print_file_to_stdout(git_path_bisect_run());
+
+             if (res == BISECT_ONLY_SKIPPED_LEFT)
+                     error(_("bisect run cannot continue any more"));
+             else if (res == BISECT_INTERNAL_SUCCESS_MERGE_BASE) {
+                     printf(_("bisect run success"));
+                     res = BISECT_OK;
+             } else if (res == BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND) {
+                     printf(_("bisect found first bad commit"));
+                     res = BISECT_OK;
+             } else if (res) {
+                     error(_("bisect run failed:'git bisect--helper --bisect-state"
+                     " %s' exited with error code %d"), args.v[0], res);
+             } else {
+                     continue;
+             }
+
+             strbuf_release(&command);
+             strvec_clear(&args);
+             strvec_clear(&run_args);
+             return res;
+     }
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
      enum {

@@ -1089,6 +1182,7 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
              BISECT_REPLAY,
              BISECT_SKIP,
              BISECT_VISUALIZE,
+             BISECT_RUN,
      } cmdmode = 0;
      int res = 0, nolog = 0;
      struct option options[] = {

@@ -1112,6 +1206,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
                       N_("skip some commits for checkout"), BISECT_SKIP),
              OPT_CMDMODE(0, "bisect-visualize", &cmdmode,
                       N_("visualize the bisection"), BISECT_VISUALIZE),
+             OPT_CMDMODE(0, "bisect-run", &cmdmode,
+                      N_("use <cmd>... to automatically bisect."), BISECT_RUN),
              OPT_BOOL(0, "no-log", &nolog,
                       N_("no log for BISECT_WRITE")),
              OPT_END()

@@ -1177,6 +1273,12 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
              get_terms(&terms);
              res = bisect_visualize(&terms, argv, argc);
              break;
+     case BISECT_RUN:
+             if (!argc)
+                     return error(_("bisect run failed: no command provided."));
+             get_terms(&terms);
+             res = bisect_run(&terms, argv, argc);
+             break;
      default:
              BUG("unknown subcommand %d", cmdmode);
      }

diff --git a/git-bisect.sh b/git-bisect.sh
index 95f7f3fb8c..e83d011e17 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh

@@ -39,66 +39,6 @@ _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 TERM_BAD=bad
 TERM_GOOD=good

-bisect_run () {
-     git bisect--helper --bisect-next-check $TERM_GOOD $TERM_BAD fail || exit
-
-     test -n "$*" || die "$(gettext "bisect run failed: no command provided.")"
-
-     while true
-     do
-             command="$@"
-             eval_gettextln "running \$command"
-             "$@"
-             res=$?
-
-             # Check for really bad run error.
-             if [ $res -lt 0 -o $res -ge 128 ]
-             then
-                     eval_gettextln "bisect run failed:
-exit code \$res from '\$command' is < 0 or >= 128" >&2
-                     exit $res
-             fi
-
-             # Find current state depending on run success or failure.
-             # A special exit code of 125 means cannot test.
-             if [ $res -eq 125 ]
-             then
-                     state='skip'
-             elif [ $res -gt 0 ]
-             then
-                     state="$TERM_BAD"
-             else
-                     state="$TERM_GOOD"
-             fi
-
-             git bisect--helper --bisect-state $state >"$GIT_DIR/BISECT_RUN"
-             res=$?
-
-             cat "$GIT_DIR/BISECT_RUN"
-
-             if sane_grep "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN" \
-                     >/dev/null
-             then
-                     gettextln "bisect run cannot continue any more" >&2
-                     exit $res
-             fi
-
-             if [ $res -ne 0 ]
-             then
-                     eval_gettextln "bisect run failed:
-'bisect-state \$state' exited with error code \$res" >&2
-                     exit $res
-             fi
-
-             if sane_grep "is the first $TERM_BAD commit" "$GIT_DIR/BISECT_RUN" >/dev/null
-             then
-                     gettextln "bisect run success"
-                     exit 0;
-             fi
-
-     done
-}
-
 get_terms () {
      if test -s "$GIT_DIR/BISECT_TERMS"
      then

@@ -137,7 +77,7 @@ case "$#" in
      log)
              git bisect--helper --bisect-log || exit ;;
      run)
-             bisect_run "$@" ;;
+             git bisect--helper --bisect-run "$@" || exit;;
      terms)
              git bisect--helper --bisect-terms "$@" || exit;;
      *)
--

2.29.2