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From: Johannes Sixt <johannes.sixt@telecom.at>
To: git@vger.kernel.org
Cc: Johannes Sixt <johannes.sixt@telecom.at>
Subject: [PATCH 15/40] Windows: A work-around for a misbehaved vsnprintf.
Date: Wed, 27 Feb 2008 19:54:38 +0100	[thread overview]
Message-ID: <1204138503-6126-16-git-send-email-johannes.sixt@telecom.at> (raw)
In-Reply-To: <1204138503-6126-1-git-send-email-johannes.sixt@telecom.at>

On Windows, vsnprintf deviates in two regards from the "usual" behavior
that its callers in GIT expect:

- It returns -1 if the buffer is too small instead of the number of
  characters that the operation produces.

- The size parameter is the number of characters to write, which does not
  include the trailing NUL byte, instead of the available space.

This wrapper computes the needed buffer size by trying various sizes with
exponential growth. A large growth factor is used so as only few trials are
required if a really large result needs to be stored.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
---
 compat/mingw.c    |   34 ++++++++++++++++++++++++++++++++++
 git-compat-util.h |    3 +++
 2 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/compat/mingw.c b/compat/mingw.c
index 4888a03..77e4b83 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -115,6 +115,40 @@ int mingw_rename(const char *pold, const char *pnew)
 	return -1;
 }
 
+#undef vsnprintf
+/* Note that the size parameter specifies the available space, i.e.
+ * includes the trailing NUL byte; but Windows's vsnprintf expects the
+ * number of characters to write without the trailing NUL.
+ */
+
+/* This is out of line because it uses alloca() behind the scenes,
+ * which must not be called in a loop (alloca() reclaims the allocations
+ * only at function exit).
+ */
+static int try_vsnprintf(size_t size, const char *fmt, va_list args)
+{
+	char buf[size];	/* gcc-ism */
+	return vsnprintf(buf, size-1, fmt, args);
+}
+
+int mingw_vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
+{
+	int len;
+	if (size > 0) {
+		len = vsnprintf(buf, size-1, fmt, args);
+		if (len >= 0)
+			return len;
+	}
+	/* ouch, buffer too small; need to compute the size */
+	if (size < 250)
+		size = 250;
+	do {
+		size *= 4;
+		len = try_vsnprintf(size, fmt, args);
+	} while (len < 0);
+	return len;
+}
+
 struct passwd *getpwuid(int uid)
 {
 	static char user_name[100];
diff --git a/git-compat-util.h b/git-compat-util.h
index 483ace2..6fa93b6 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -602,6 +602,9 @@ char *mingw_getcwd(char *pointer, int len);
 int mingw_rename(const char*, const char*);
 #define rename mingw_rename
 
+int mingw_vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
+#define vsnprintf mingw_vsnprintf
+
 sig_handler_t mingw_signal(int sig, sig_handler_t handler);
 #define signal mingw_signal
 
-- 
1.5.4.1.126.ge5a7d

  parent reply	other threads:[~2008-02-27 18:59 UTC|newest]

Thread overview: 138+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-27 18:54 [PATCH 00/40] MinGW port Johannes Sixt
2008-02-27 18:54 ` [PATCH 01/40] Add compat/regex.[ch] and compat/fnmatch.[ch] Johannes Sixt
2008-02-27 23:43   ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 02/40] Compile some programs only conditionally Johannes Sixt
2008-02-28 11:57   ` Johannes Schindelin
2008-02-28 20:30     ` Johannes Sixt
2008-02-29  0:47       ` Johannes Schindelin
2008-02-29 20:58         ` Johannes Sixt
2008-02-29 21:53           ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 03/40] Add target architecture MinGW Johannes Sixt
2008-02-28 12:05   ` Johannes Schindelin
2008-02-28 12:57     ` Paolo Bonzini
2008-02-28 14:56       ` Johannes Schindelin
2008-02-28 20:40     ` Johannes Sixt
2008-02-29  1:07       ` Johannes Schindelin
2008-02-29 21:03         ` Johannes Sixt
2008-02-29 21:54           ` Johannes Schindelin
2008-03-05 21:21     ` Johannes Sixt
2008-03-05 22:18       ` Johannes Schindelin
2008-03-05 22:22         ` Junio C Hamano
2008-03-05 22:28           ` Johannes Schindelin
2008-03-05 22:51             ` Junio C Hamano
2008-03-06  0:11               ` Johannes Schindelin
2008-03-06  1:14             ` [PATCH 1/2] Add strbuf_initf() Johannes Schindelin
2008-03-06  6:33               ` Mike Hommey
2008-03-06  9:03                 ` Reece Dunn
2008-03-06 10:55                   ` Johannes Schindelin
2008-03-06 11:53                     ` Reece Dunn
2008-03-06 12:52                       ` Johannes Schindelin
2008-03-06 16:29                         ` [PATCH 1/2 v2] Add strbuf_vaddf(), use it in strbuf_addf(), and add strbuf_initf() Johannes Schindelin
2008-03-06 16:38                           ` Johannes Sixt
2008-03-06 16:47                             ` Johannes Sixt
2008-03-06 16:59                               ` Johannes Schindelin
2008-03-06 18:18                     ` [PATCH 1/2] Add strbuf_initf() Kristian Høgsberg
2008-03-06 18:26                       ` Johannes Schindelin
2008-03-06 18:35                         ` Kristian Høgsberg
2008-03-06 19:10                         ` Mike Hommey
2008-03-06 10:53                 ` Johannes Schindelin
2008-03-06 12:09                   ` Jeff King
2008-03-06  1:15             ` [PATCH 2/2] format-patch: add --reviewed-by=<ident> Johannes Schindelin
2008-03-06  2:40               ` Junio C Hamano
2008-03-06 10:40                 ` Johannes Schindelin
2008-03-06 20:38         ` [PATCH 03/40] Add target architecture MinGW Johannes Sixt
2008-03-11 21:30       ` Johannes Sixt
2008-03-11 23:28         ` Johannes Schindelin
2008-03-12 22:59           ` Johannes Sixt
2008-03-12 23:06             ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 04/40] Windows: Use the Windows style PATH separator ';' Johannes Sixt
2008-02-28  9:25   ` Paolo Bonzini
2008-02-28 20:43     ` Johannes Sixt
2008-02-29  1:09       ` Johannes Schindelin
2008-02-29  7:57       ` Paolo Bonzini
2008-02-29 12:19         ` Johannes Schindelin
2008-02-29 12:45           ` Paolo Bonzini
2008-02-29 12:59             ` Johannes Schindelin
2008-02-28 17:57   ` Junio C Hamano
2008-02-27 18:54 ` [PATCH 05/40] Windows: Strip ".exe" from the program name Johannes Sixt
2008-02-27 18:54 ` [PATCH 06/40] Windows: Implement a wrapper of the open() function Johannes Sixt
2008-02-27 18:54 ` [PATCH 07/40] Windows: A minimal implemention of getpwuid() Johannes Sixt
2008-02-27 18:54 ` [PATCH 08/40] Windows: always chmod(, 0666) before unlink() Johannes Sixt
2008-02-28 12:09   ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 09/40] Windows: Work around misbehaved rename() Johannes Sixt
2008-02-27 18:54 ` [PATCH 10/40] Windows: Treat Windows style path names Johannes Sixt
2008-02-28 12:18   ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 11/40] Windows: Handle absolute paths in safe_create_leading_directories() Johannes Sixt
2008-02-27 18:54 ` [PATCH 12/40] Windows: Implement gettimeofday() Johannes Sixt
2008-02-27 18:54 ` [PATCH 13/40] Windows: Fix PRIuMAX definition Johannes Sixt
2008-02-28 12:21   ` Johannes Schindelin
2008-02-28 20:45     ` Johannes Sixt
2008-02-27 18:54 ` [PATCH 14/40] Windows: Implement setitimer() and sigaction() Johannes Sixt
2008-02-27 18:54 ` Johannes Sixt [this message]
2008-02-27 18:54 ` [PATCH 16/40] Windows: Wrap execve so that shell scripts can be invoked Johannes Sixt
2008-02-27 18:54 ` [PATCH 17/40] Windows: A pipe() replacement whose ends are not inherited to children Johannes Sixt
2008-02-27 18:54 ` [PATCH 18/40] Windows: Implement start_command() Johannes Sixt
2008-02-27 18:54 ` [PATCH 19/40] Windows: Change the name of hook scripts to make them not executable Johannes Sixt
2008-02-28 15:20   ` Johannes Schindelin
2008-02-28 20:48     ` Johannes Sixt
2008-02-29  1:11       ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 20/40] Windows: A rudimentary poll() emulation Johannes Sixt
2008-02-28  9:36   ` Paolo Bonzini
2008-02-28 20:49     ` Johannes Sixt
     [not found]       ` <5d46db230802282019o21f9ed9fo75fed8744625289e@mail.gmail.com>
     [not found]         ` <200802292216.25014.johannes.sixt@telecom.at>
2008-02-29 21:47           ` Govind Salinas
2008-02-29 22:16             ` Johannes Sixt
2008-02-29 23:17             ` Brian Dessent
2008-03-01 15:48       ` Robin Rosenberg
2008-03-01 19:24         ` Johannes Sixt
2008-02-27 18:54 ` [PATCH 21/40] Windows: Disambiguate DOS style paths from SSH URLs Johannes Sixt
2008-02-28 15:22   ` Johannes Schindelin
2008-02-28 20:51     ` Johannes Sixt
2008-02-27 18:54 ` [PATCH 22/40] Windows: Implement asynchronous functions as threads Johannes Sixt
2008-02-28 15:28   ` Johannes Schindelin
2008-02-28 17:48     ` Paul Franz
2008-02-29  1:27       ` Johannes Schindelin
2008-02-29  1:46         ` Paul Franz
2008-02-29  1:54           ` Johannes Schindelin
2008-02-29  3:08             ` Paul Franz
2008-02-29  7:51               ` Junio C Hamano
2008-02-29 11:45                 ` Paul Franz
2008-02-29 10:26               ` Johannes Schindelin
2008-02-28 21:01     ` Johannes Sixt
2008-02-29  1:17       ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 23/40] Windows: Local clone must use the drive letter in absolute paths Johannes Sixt
2008-02-28 15:31   ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 24/40] Windows: Work around incompatible sort and find Johannes Sixt
2008-02-27 18:54 ` [PATCH 25/40] Windows: Implement a cpio emulation in git-clone.sh Johannes Sixt
2008-02-27 18:54 ` [PATCH 26/40] Windows: Implement wrappers for gethostbyname(), socket(), and connect() Johannes Sixt
2008-02-27 18:54 ` [PATCH 27/40] Windows: Implement a custom spawnve() Johannes Sixt
2008-02-28 15:36   ` Johannes Schindelin
2008-02-28 21:04     ` Johannes Sixt
2008-02-29  1:18       ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 28/40] Windows: Add a new lstat and fstat implementation based on Win32 API Johannes Sixt
2008-02-27 18:54 ` [PATCH 29/40] Windows: Use a customized struct stat that also has the st_blocks member Johannes Sixt
2008-02-27 18:54 ` [PATCH 30/40] Turn builtin_exec_path into a function Johannes Sixt
2008-02-27 18:54 ` [PATCH 31/40] Compute the ultimate fallback for exec_path from the program invocation Johannes Sixt
2008-02-27 18:54 ` [PATCH 32/40] Windows: Use a relative default template_dir and ETC_GITCONFIG Johannes Sixt
2008-02-27 18:54 ` [PATCH 33/40] When installing, be prepared that template_dir may be relative Johannes Sixt
2008-02-28  9:49   ` Paolo Bonzini
2008-02-28 15:45   ` Johannes Schindelin
2008-02-28 15:57     ` Paolo Bonzini
2008-02-28 21:12     ` Johannes Sixt
2008-02-29  1:21       ` Johannes Schindelin
2008-02-27 18:54 ` [PATCH 34/40] Windows: Make the pager work Johannes Sixt
2008-02-27 18:54 ` [PATCH 35/40] Windows: Work around an oddity when a pipe with no reader is written to Johannes Sixt
2008-02-27 18:54 ` [PATCH 36/40] Avoid the "dup dance" in wt_status_print_verbose() when possible Johannes Sixt
2008-02-28 15:48   ` Johannes Schindelin
2008-02-27 18:55 ` [PATCH 37/40] Windows: Make 'git help -a' work Johannes Sixt
2008-02-28  9:52   ` Paolo Bonzini
2008-02-27 18:55 ` [PATCH 38/40] Windows: TMP and TEMP environment variables specify a temporary directory Johannes Sixt
2008-02-27 18:55 ` [PATCH 39/40] Windows: Fix ntohl() related warnings about printf formatting Johannes Sixt
2008-02-27 18:55 ` [PATCH 40/40] compat/pread.c: Add foward decl to fix warning Johannes Sixt
2008-02-28 15:51   ` Johannes Schindelin
2008-02-27 22:01 ` [PATCH 00/40] MinGW port Marius Storm-Olsen
2008-02-27 23:34   ` Martin Langhoff
2008-02-28  3:38     ` Nguyen Thai Ngoc Duy
2008-02-27 23:58 ` Johannes Schindelin
2008-03-02 21:20 ` Johannes Sixt
2008-03-02 22:07   ` Johannes Schindelin
2008-03-03 18:34     ` Johannes Sixt

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