diff --git a/linux-user/mmap.c b/linux-user/mmap.c index 6418e811f6..e4bf5d5f39 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -283,6 +283,40 @@ static int do_munmap(void *addr, size_t len) return munmap(addr, len); } +/* + * Perform a pread on behalf of target_mmap. We can reach EOF, we can be + * interrupted by signals, and in general there's no good error return path. + * If @zero, zero the rest of the block at EOF. + * Return true on success. + */ +static bool mmap_pread(int fd, void *p, size_t len, off_t offset, bool zero) +{ + while (1) { + ssize_t r = pread(fd, p, len, offset); + + if (likely(r == len)) { + /* Complete */ + return true; + } + if (r == 0) { + /* EOF */ + if (zero) { + memset(p, 0, len); + } + return true; + } + if (r > 0) { + /* Short read */ + p += r; + len -= r; + offset += r; + } else if (errno != EINTR) { + /* Error */ + return false; + } + } +} + /* * Map an incomplete host page. * @@ -357,10 +391,9 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last, /* Read or zero the new guest pages. */ if (flags & MAP_ANONYMOUS) { memset(g2h_untagged(start), 0, last - start + 1); - } else { - if (pread(fd, g2h_untagged(start), last - start + 1, offset) == -1) { - return false; - } + } else if (!mmap_pread(fd, g2h_untagged(start), last - start + 1, + offset, true)) { + return false; } /* Put final protection */ @@ -853,8 +886,7 @@ static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len, } if (misaligned_offset) { - /* TODO: The read could be short. */ - if (pread(fd, p, host_len, offset + real_start - start) != host_len) { + if (!mmap_pread(fd, p, host_len, offset + real_start - start, false)) { do_munmap(p, host_len); return -1; }