Re: [PATCH v2] commit: fix memory-leak

On Mon, Feb 7, 2011 at 10:12 PM, Erik Faye-Lund [off-list ref] wrote:

On Mon, Feb 7, 2011 at 9:21 PM, Erik Faye-Lund [off-list ref] wrote:

quoted

The name, email and date strings are some times allocated on the
heap, but not free'd. Fix this by making sure they are allways
heap-allocated, so we can safely free the memory.

At the same time, this fixes a problem with strict-POSIX getenv
implementations. POSIX says "The return value from getenv() may
point to static data which may be overwritten by subsequent calls
to getenv()", so not duplicating the strings is a potential bug.

Signed-off-by: Erik Faye-Lund <redacted>
---
Fixed typo in commit message, as pointed out by Matthieu Moy.

 builtin/commit.c  |    9 ++++++---
 git-compat-util.h |    1 +
 wrapper.c         |    6 ++++++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index 03cff5a..e5a649e 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c

@@ -465,9 +465,9 @@ static void determine_author_info(struct strbuf *author_ident)

 {
       char *name, *email, *date;

-       name = getenv("GIT_AUTHOR_NAME");
-       email = getenv("GIT_AUTHOR_EMAIL");
-       date = getenv("GIT_AUTHOR_DATE");
+       name = xgetenv("GIT_AUTHOR_NAME");
+       email = xgetenv("GIT_AUTHOR_EMAIL");
+       date = xgetenv("GIT_AUTHOR_DATE");

       if (use_message && !renew_authorship) {
               const char *a, *lb, *rb, *eol;

@@ -507,6 +507,9 @@ static void determine_author_info(struct strbuf *author_ident)

               date = force_date;
       strbuf_addstr(author_ident, fmt_ident(name, email, date,
                                             IDENT_ERROR_ON_NO_NAME));
+       free(name);
+       free(email);
+       free(date);

Hmm, but I'm getting a crash here on Linux. Guess I need to debug a bit...

Ah, it was the force_date-assignment:
---8<---

diff --git a/builtin/commit.c b/builtin/commit.c
index e5a649e..1416c13 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c

@@ -504,7 +504,7 @@ static void determine_author_info(struct strbuf

*author_ident)
 	}

 	if (force_date)
-		date = force_date;
+		date = xstrdup(force_date);
 	strbuf_addstr(author_ident, fmt_ident(name, email, date,
 					      IDENT_ERROR_ON_NO_NAME));
 	free(name);

---8<---

But now I see that I was temporarily(?) struck with insanity:
overwriting a heap-allocated pointer with another heap-allocated
pointer doesn't fix a memory-leak. So let's add some more calls to
free:

diff --git a/builtin/commit.c b/builtin/commit.c
index e5a649e..bdd0cfb 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c

@@ -482,6 +482,10 @@ static void determine_author_info(struct strbuf

*author_ident)
 		if (!*lb || !*rb || !*eol)
 			die("invalid commit: %s", use_message);

+		free(name);
+		free(email);
+		free(date);
+
 		if (lb == a + strlen("\nauthor "))
 			/* \nauthor [off-list ref] */
 			name = xcalloc(1, 1);

@@ -497,14 +501,19 @@ static void determine_author_info(struct strbuf

*author_ident)
 		const char *lb = strstr(force_author, " <");
 		const char *rb = strchr(force_author, '>');

+		free(name);
+		free(email);
+
 		if (!lb || !rb)
 			die("malformed --author parameter");
 		name = xstrndup(force_author, lb - force_author);
 		email = xstrndup(lb + 2, rb - (lb + 2));
 	}

-	if (force_date)
-		date = force_date;
+	if (force_date) {
+		free(date);
+		date = xstrdup(force_date);
+	}
 	strbuf_addstr(author_ident, fmt_ident(name, email, date,
 					      IDENT_ERROR_ON_NO_NAME));
 	free(name);