Improve error message when packfile mmap fails.

If we are unable to mmap the a region of the packfile with the mmap()
system call there may be a good reason why, such as a closed file
descriptor or out of address space.  Reporting the system level
error message can help to debug such problems.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/sha1_file.c b/sha1_file.c
index 548535c8448430457ae9dd4e1507166efbea8551..63123cc47be29430565f594340374271248f01bc 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -590,7 +590,9 @@ unsigned char* use_pack(struct packed_git *p,
                                PROT_READ, MAP_PRIVATE,
                                p->pack_fd, win->offset);
                        if (win->base == MAP_FAILED)
-                               die("packfile %s cannot be mapped.", p->pack_name);
+                               die("packfile %s cannot be mapped: %s",
+                                       p->pack_name,
+                                       strerror(errno));
                        win->next = p->windows;
                        p->windows = win;
                }