[PATCH] Replacing the system call pread() with lseek()/xread()/lseek() sequence.
- From
- Stefan-W. Hahn <stefan.hahn@s-hahn.de>
- Date
- Jan 9, 2007, 18:51 UTC
- Message-ID
- <41319.3372231492$1168368741@news.gmane.org>
- In-Reply-To
- <11683687162492-git-send-email->
From: Stefan-W. Hahn <stefan.hahn@s-hahn.de>
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> --- Makefile | 7 +++++++ compat/pread.c | 15 +++++++++++++++ git-compat-util.h | 5 +++++ 3 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/Makefile b/Makefile index 6c12bc6..47af0de 100644 --- a/Makefile +++ b/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 (i.e. +# 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 diff --git a/compat/pread.c b/compat/pread.c new file mode 100644 index 0000000..cd1da87 --- /dev/null +++ b/compat/pread.c @@ -0,0 +1,15 @@ +#include "../git-compat-util.h" + +ssize_t git_pread(int fd,void *buf,size_t count,off_t offset) +{ + off_t current_offset = lseek(fd, 0, SEEK_CUR); + + if (lseek(fd, offset, SEEK_SET) < 0) + return EINVAL; + + ssize_t rc=xread(fd, buf, count); + + if (current_offset != lseek(fd, current_offset, SEEK_SET)) + return EINVAL; + return rc; +} diff --git a/git-compat-util.h b/git-compat-util.h index e023bf1..00b14df 100644 --- a/git-compat-util.h +++ b/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);
-- 1.4.4.4.g46aa