From c4712e4553f13d87d655325a57538f299402d457 Mon Sep 17 00:00:00 2001 From: "Shawn O. Pearce" Date: Sun, 24 Dec 2006 00:47:23 -0500 Subject: [PATCH] Replace mmap with xmmap, better handling MAP_FAILED. In some cases we did not even bother to check the return value of mmap() and just assume it worked. This is bad, because if we are out of virtual address space the kernel returned MAP_FAILED and we would attempt to dereference that address, segfaulting without any real error output to the user. We are replacing all calls to mmap() with xmmap() and moving all MAP_FAILED checking into that single location. If a mmap call fails we try to release enough least-recently-used pack windows to possibly succeed, then retry the mmap() attempt. If we cannot mmap even after releasing pack memory then we die() as none of our callers have any reasonable recovery strategy for a failed mmap. Signed-off-by: Shawn O. Pearce Signed-off-by: Junio C Hamano --- config.c | 2 +- diff.c | 4 +--- git-compat-util.h | 13 +++++++++++++ read-cache.c | 2 +- refs.c | 2 +- sha1_file.c | 18 +++++------------- 6 files changed, 22 insertions(+), 19 deletions(-) diff --git a/config.c b/config.c index 3b8da569f..2e0d5a868 100644 --- a/config.c +++ b/config.c @@ -704,7 +704,7 @@ int git_config_set_multivar(const char* key, const char* value, } fstat(in_fd, &st); - contents = mmap(NULL, st.st_size, PROT_READ, + contents = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, in_fd, 0); close(in_fd); diff --git a/diff.c b/diff.c index f14288bb8..244292a70 100644 --- a/diff.c +++ b/diff.c @@ -1341,10 +1341,8 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only) fd = open(s->path, O_RDONLY); if (fd < 0) goto err_empty; - s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0); + s->data = xmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0); close(fd); - if (s->data == MAP_FAILED) - goto err_empty; s->should_munmap = 1; } else { diff --git a/git-compat-util.h b/git-compat-util.h index 0f856747e..f243b86d3 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -188,6 +188,19 @@ static inline void *xcalloc(size_t nmemb, size_t size) return ret; } +static inline void *xmmap(void *start, size_t length, + int prot, int flags, int fd, off_t offset) +{ + void *ret = mmap(start, length, prot, flags, fd, offset); + if (ret == MAP_FAILED) { + release_pack_memory(length); + ret = mmap(start, length, prot, flags, fd, offset); + if (ret == MAP_FAILED) + die("Out of memory? mmap failed: %s", strerror(errno)); + } + return ret; +} + static inline ssize_t xread(int fd, void *buf, size_t len) { ssize_t nr; diff --git a/read-cache.c b/read-cache.c index b8d83ccd9..ca3efbbf0 100644 --- a/read-cache.c +++ b/read-cache.c @@ -798,7 +798,7 @@ int read_cache_from(const char *path) cache_mmap_size = st.st_size; errno = EINVAL; if (cache_mmap_size >= sizeof(struct cache_header) + 20) - cache_mmap = mmap(NULL, cache_mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); + cache_mmap = xmmap(NULL, cache_mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); } close(fd); if (cache_mmap == MAP_FAILED) diff --git a/refs.c b/refs.c index e88ed8b2d..121774cb3 100644 --- a/refs.c +++ b/refs.c @@ -1026,7 +1026,7 @@ int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char * fstat(logfd, &st); if (!st.st_size) die("Log %s is empty.", logfile); - logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0); + logdata = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0); close(logfd); lastrec = NULL; diff --git a/sha1_file.c b/sha1_file.c index fb1032b0f..84037fe98 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -355,10 +355,8 @@ static void read_info_alternates(const char * relative_base, int depth) close(fd); return; } - map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); + map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); close(fd); - if (map == MAP_FAILED) - return; link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth); @@ -442,10 +440,8 @@ static int check_packed_git_idx(const char *path, unsigned long *idx_size_, return -1; } idx_size = st.st_size; - idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0); + idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0); close(fd); - if (idx_map == MAP_FAILED) - return -1; index = idx_map; *idx_map_ = idx_map; @@ -630,7 +626,7 @@ unsigned char* use_pack(struct packed_git *p, while (packed_git_limit < pack_mapped && unuse_one_window(p)) ; /* nothing */ - win->base = mmap(NULL, win->len, + win->base = xmmap(NULL, win->len, PROT_READ, MAP_PRIVATE, p->pack_fd, win->offset); if (win->base == MAP_FAILED) @@ -828,10 +824,8 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size) */ sha1_file_open_flag = 0; } - map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); + map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0); close(fd); - if (map == MAP_FAILED) - return NULL; *size = st.st_size; return map; } @@ -1987,10 +1981,8 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, con buf = ""; if (size) - buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); + buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); close(fd); - if (buf == MAP_FAILED) - return -1; if (!type) type = blob_type; -- 2.30.2