Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Browse files

Replacing the system call pread() with lseek()/xread()/lseek() sequence.

Using cygwin with cygwin.dll before 1.5.22 the system call pread() is buggy.
This patch introduces NO_PREAD. If NO_PREAD is set git uses a sequence of
lseek()/xread()/lseek() to emulate pread.

Signed-off-by: Stefan-W. Hahn <stefan.hahn@s-hahn.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
  • Loading branch information...
commit 6900679c2f6d937a5a6ef616869c8887690ad19d 1 parent 0bdb28c
Stefan-W. Hahn authored Junio C Hamano committed
Showing with 30 additions and 0 deletions.
  1. +7 −0 Makefile
  2. +18 −0 compat/pread.c
  3. +5 −0 git-compat-util.h
View
7 Makefile
@@ -69,6 +69,9 @@ all:
#
# Define NO_MMAP if you want to avoid mmap.
#
+# Define NO_PREAD if you have a problem with pread() system call (e.g.
+# cygwin.dll before v1.5.22).
+#
# Define NO_FAST_WORKING_DIRECTORY if accessing objects in pack files is
# generally faster on your platform than accessing the working directory.
#
@@ -523,6 +526,10 @@ ifdef NO_MMAP
COMPAT_CFLAGS += -DNO_MMAP
COMPAT_OBJS += compat/mmap.o
endif
+ifdef NO_PREAD
+ COMPAT_CFLAGS += -DNO_PREAD
+ COMPAT_OBJS += compat/pread.o
+endif
ifdef NO_FAST_WORKING_DIRECTORY
BASIC_CFLAGS += -DNO_FAST_WORKING_DIRECTORY
endif
View
18 compat/pread.c
@@ -0,0 +1,18 @@
+#include "../git-compat-util.h"
+
+ssize_t git_pread(int fd, void *buf, size_t count, off_t offset)
+{
+ off_t current_offset;
+ ssize_t rc;
+
+ current_offset = lseek(fd, 0, SEEK_CUR);
+
+ if (lseek(fd, offset, SEEK_SET) < 0)
+ return -1;
+
+ rc = read_in_full(fd, buf, count);
+
+ if (current_offset != lseek(fd, current_offset, SEEK_SET))
+ return -1;
+ return rc;
+}
View
5 git-compat-util.h
@@ -107,6 +107,11 @@ extern int git_munmap(void *start, size_t length);
#define DEFAULT_PACKED_GIT_LIMIT \
((1024L * 1024L) * (sizeof(void*) >= 8 ? 8192 : 256))
+#ifdef NO_PREAD
+#define pread git_pread
+extern ssize_t git_pread(int fd, void *buf, size_t count, off_t offset);
+#endif
+
#ifdef NO_SETENV
#define setenv gitsetenv
extern int gitsetenv(const char *, const char *, int);
Please sign in to comment.
Something went wrong with that request. Please try again.