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[PATCH v4 2/2] sequencer: fix quoting in write_author_script

From
PWPhillip Wood <phillip.wood@talktalk.net>
Date
Aug 7, 2018, 09:34 UTC
Message-ID
<20180807093452.22524-3-phillip.wood@talktalk.net>
In-Reply-To
<20180807093452.22524-1-phillip.wood@talktalk.net>
From: Phillip Wood <phillip.wood@dunelm.org.uk>

Single quotes should be escaped as \' not \\'. The bad quoting breaks the interactive version of 'rebase --root' (which is used when there is no '--onto' even if the user does not specify --interactive) for authors that contain "'" as sq_dequote() called by read_author_ident() errors out on the bad quoting.

For other interactive rebases this only affects external scripts that read the author script and users whose git is upgraded from the shell version of rebase -i while rebase was stopped when the author contains "'". This is because the parsing in read_env_script() expected the broken quoting.

This patch includes code to handle the broken quoting when git has been upgraded while rebase was stopped. It does this by detecting the missing "'" at the end of the GIT_AUTHOR_DATE line to see if it should dequote \\' as "'". Note this is only implemented for normal picks, not for creating a new root commit (rebase will stop with an error complaining out bad quoting in that case).

The fallback code has been manually tested by reverting both the quoting fixes in write_author_script() and the previous fix for the missing "'" at the end of the GIT_AUTHOR_DATE line and running t3404-rebase-interactive.sh.

Ideally rebase and am would share the same code for reading and writing the author script, but this commit just fixes the immediate bug.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---
Notes:
    changes since v3:
    
     - Reverted the implementation to v2 with more robust detection of the
       missing "'" on the last line of the author script based on a
       suggestion by Eric. This means that this series needs to progress
       closely with Eric's series of fixes or the fallback code will never
       be called.
    
    - Tweaked the last test
 sequencer.c                   | 36 ++++++++++++++++++++++++++++-------
 t/t3404-rebase-interactive.sh | 18 +++++++++++++++---
 2 files changed, 44 insertions(+), 10 deletions(-)
diff --git a/sequencer.c b/sequencer.c
index c4e4418559..ba11fe5bca 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -636,42 +636,64 @@ static int write_author_script(const char *message)
 		else if (*message != '\'')
 			strbuf_addch(&buf, *(message++));
 		else
-			strbuf_addf(&buf, "'\\\\%c'", *(message++));
+			strbuf_addf(&buf, "'\\%c'", *(message++));
 	strbuf_addstr(&buf, "'\nGIT_AUTHOR_EMAIL='");
 	while (*message && *message != '\n' && *message != '\r')
 		if (skip_prefix(message, "> ", &message))
 			break;
 		else if (*message != '\'')
 			strbuf_addch(&buf, *(message++));
 		else
-			strbuf_addf(&buf, "'\\\\%c'", *(message++));
+			strbuf_addf(&buf, "'\\%c'", *(message++));
 	strbuf_addstr(&buf, "'\nGIT_AUTHOR_DATE='@");
 	while (*message && *message != '\n' && *message != '\r')
 		if (*message != '\'')
 			strbuf_addch(&buf, *(message++));
 		else
-			strbuf_addf(&buf, "'\\\\%c'", *(message++));
+			strbuf_addf(&buf, "'\\%c'", *(message++));
 	strbuf_addch(&buf, '\'');
 	res = write_message(buf.buf, buf.len, rebase_path_author_script(), 1);
 	strbuf_release(&buf);
 	return res;
 }
 
+
+/*
+ * write_author_script() used to fail to terminate the last line with a "'" and
+ * also escaped "'" incorrectly as "'\\\\''" rather than "'\\''". We check for
+ * the terminating "'" on the last line to see how "'" has been escaped in case
+ * git was upgraded while rebase was stopped.
+ */
+static int quoting_is_broken(const char *s, size_t n)
+{
+	/* Skip any empty lines in case the file was hand edited */
+	while (n > 0 && s[--n] == '\n')
+		; /* empty */
+	if (n > 0 && s[n] != '\'')
+		return 1;
+
+	return 0;
+}
+
 /*
  * Read a list of environment variable assignments (such as the author-script
  * file) into an environment block. Returns -1 on error, 0 otherwise.
  */
 static int read_env_script(struct argv_array *env)
 {
 	struct strbuf script = STRBUF_INIT;
-	int i, count = 0;
-	char *p, *p2;
+	int i, count = 0, sq_bug;
+	const char *p2;
+	char *p;
 
 	if (strbuf_read_file(&script, rebase_path_author_script(), 256) <= 0)
 		return -1;
-
+	/* write_author_script() used to quote incorrectly */
+	sq_bug = quoting_is_broken(script.buf, script.len);
 	for (p = script.buf; *p; p++)
-		if (skip_prefix(p, "'\\\\''", (const char **)&p2))
+		if (sq_bug && skip_prefix(p, "'\\\\''", &p2))
+			strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
+		else if (skip_prefix(p, "'\\''", &p2))
 			strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
 		else if (*p == '\'')
 			strbuf_splice(&script, p-- - script.buf, 1, "", 0);
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index b72167ecd5..834a124d60 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -1382,9 +1382,21 @@ test_expect_success 'rebase -i --gpg-sign=<key-id> overrides commit.gpgSign' '
 test_expect_success 'valid author header after --root swap' '
 	rebase_setup_and_clean author-header no-conflict-branch &&
 	set_fake_editor &&
-	FAKE_LINES="2 1" git rebase -i --root &&
-	git cat-file commit HEAD^ >out &&
-	grep "^author ..*> [0-9][0-9]* [-+][0-9][0-9][0-9][0-9]$" out
+	git commit --amend --author="Au ${SQ}thor <author@example.com>" --no-edit &&
+	git cat-file commit HEAD | grep ^author >expected &&
+	FAKE_LINES="5 1" git rebase -i --root &&
+	git cat-file commit HEAD^ | grep ^author >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'valid author header when author contains single quote' '
+	rebase_setup_and_clean author-header no-conflict-branch &&
+	set_fake_editor &&
+	git commit --amend --author="Au ${SQ}thor <author@example.com>" --no-edit &&
+	git cat-file commit HEAD | grep ^author >expected &&
+	FAKE_LINES="2" git rebase -i HEAD~2 &&
+	git cat-file commit HEAD | grep ^author >actual &&
+	test_cmp expected actual
 '
 
 test_done
-- 
2.18.0
Previous: Eric SunshineNext: Eric Sunshine
Message 48 of 57 in “fix "rebase -i --root" corrupting root commit”
  1. 0/4 fix "rebase -i --root" corrupting root commitEric Sunshine, Jul 31, 2018
  2. 1/4 sequencer: fix "rebase -i --root" corrupting author headerEric Sunshine, Jul 31, 2018
  3. 2/4 sequencer: fix "rebase -i --root" corrupting author header timezoneEric Sunshine, Jul 31, 2018
  4. Phillip WoodJul 31, 2018
  5. Eric SunshineJul 31, 2018
  6. 4/4 sequencer: don't die() on bogus user-edited timestampEric Sunshine, Jul 31, 2018
  7. Phillip WoodJul 31, 2018
  8. Eric SunshineJul 31, 2018
  9. 3/4 sequencer: fix "rebase -i --root" corrupting author header timestampEric Sunshine, Jul 31, 2018
  10. Phillip WoodJul 31, 2018
  11. Eric SunshineJul 31, 2018
  12. Phillip WoodJul 31, 2018
  13. Eric SunshineJul 31, 2018
  14. Phillip WoodJul 31, 2018
  15. Eric SunshineJul 31, 2018
  16. 0/2 Fix author script quotingPhillip Wood, Jul 31, 2018
  17. 1/2 sequencer: handle errors in read_author_ident()Phillip Wood, Jul 31, 2018
  18. Eric SunshineJul 31, 2018
  19. Phillip WoodAug 1, 2018
  20. 2/2 sequencer: fix quoting in write_author_scriptPhillip Wood, Jul 31, 2018
  21. Eric SunshineJul 31, 2018
  22. Phillip WoodAug 1, 2018
  23. Junio C HamanoAug 1, 2018
  24. Phillip WoodAug 1, 2018
  25. Eric SunshineAug 1, 2018
  26. Hilco WijbengaAug 1, 2018
  27. Eric SunshineAug 1, 2018
  28. Hilco WijbengaAug 7, 2018
  29. Eric SunshineAug 7, 2018
  30. Junio C HamanoAug 7, 2018
  31. Johannes SchindelinAug 27, 2018
  32. brian m. carlsonAug 1, 2018
  33. Eric SunshineAug 2, 2018
  34. 0/2 Fix author script quotingPhillip Wood, Aug 2, 2018
  35. 1/2 sequencer: handle errors in read_author_ident()Phillip Wood, Aug 2, 2018
  36. Eric SunshineAug 3, 2018
  37. Junio C HamanoAug 3, 2018
  38. 2/2 sequencer: fix quoting in write_author_scriptPhillip Wood, Aug 2, 2018
  39. Junio C HamanoAug 2, 2018
  40. Eric SunshineAug 3, 2018
  41. Phillip WoodAug 3, 2018
  42. Eric SunshineAug 3, 2018
  43. Phillip WoodAug 3, 2018
  44. Junio C HamanoAug 7, 2018
  45. 0/2 fix author-script quotingPhillip Wood, Aug 7, 2018
  46. 1/2 sequencer: handle errors from read_author_ident()Phillip Wood, Aug 7, 2018
  47. Eric SunshineAug 8, 2018
  48. 2/2 sequencer: fix quoting in write_author_scriptPhillip Wood, Aug 7, 2018
  49. Eric SunshineAug 7, 2018
  50. Phillip WoodAug 7, 2018
  51. Eric SunshineAug 8, 2018
  52. Junio C HamanoAug 8, 2018
  53. Phillip WoodAug 9, 2018
  54. Phillip WoodAug 9, 2018
  55. Eric SunshineAug 8, 2018
  56. Phillip WoodAug 9, 2018
  57. Eric SunshineAug 8, 2018

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