On further thought, the heuristic is also incorrect for file
systems that compress their data. So I installed this further
patch.
Oh, well. At least the code is simpler now. Simple and slow
is better than complicated and fast and occasionally wrong.
From 1af34b9d2bf3b6c7abf3668d67d5e78097c35006 Mon Sep 17 00:00:00 2001
From: Paul Eggert <address@hidden>
Date: Fri, 27 Jul 2012 14:35:26 -0700
Subject: [PATCH] grep: don't falsely report compressed text files as binary
* NEWS: Document this.
* src/main.c (file_is_binary): Remove the heuristic based on
st_blocks, as it does not work for compressed file systems.
On Solaris, it'd be cheap to test whether the file system is known
to be uncompressed, which allow the heuristic, but Solaris has
SEEK_HOLE so there's little point.
---
NEWS | 4 ++--
src/main.c | 39 +++++++--------------------------------
2 files changed, 9 insertions(+), 34 deletions(-)
diff --git a/NEWS b/NEWS
index 753aedc..fdba25e 100644
--- a/NEWS
+++ b/NEWS
@@ -4,8 +4,8 @@ GNU grep NEWS -*- outline -*-
** Bug fixes
- 'grep' no longer falsely reports tiny text files as being binary
- on file systems that store tiny files' contents in metadata.
+ 'grep' no longer falsely reports text files as being binary on file
+ systems that compress contents or that store tiny contents in metadata.
* Noteworthy changes in release 2.13 (2012-07-04) [stable]
diff --git a/src/main.c b/src/main.c
index 96e4f37..6954760 100644
--- a/src/main.c
+++ b/src/main.c
@@ -443,9 +443,6 @@ clean_up_stdout (void)
static int
file_is_binary (char const *buf, size_t bufsize, int fd, struct stat const *st)
{
- #ifndef HAVE_STRUCT_STAT_ST_BLOCKS
- enum { HAVE_STRUCT_STAT_ST_BLOCKS = 0 };
- #endif
#ifndef SEEK_HOLE
enum { SEEK_HOLE = SEEK_END };
#endif
@@ -461,8 +458,7 @@ file_is_binary (char const *buf, size_t bufsize, int fd,
struct stat const *st)
return 1;
/* If the file has holes, it must contain a null byte somewhere. */
- if ((HAVE_STRUCT_STAT_ST_BLOCKS || SEEK_HOLE != SEEK_END)
- && usable_st_size (st))
+ if (SEEK_HOLE != SEEK_END && usable_st_size (st))
{
off_t cur = bufsize;
if (O_BINARY || fd == STDIN_FILENO)
@@ -472,35 +468,14 @@ file_is_binary (char const *buf, size_t bufsize, int fd,
struct stat const *st)
return 0;
}
- /* If the file has fewer blocks than would be needed to
- represent its data, then it must have at least one hole. */
- if (HAVE_STRUCT_STAT_ST_BLOCKS)
- {
- /* Some servers store tiny files using zero blocks, so skip
- this check at apparent EOF, to avoid falsely reporting
- that a tiny zero-block file is binary. */
- off_t not_yet_read = st->st_size - cur;
- if (0 < not_yet_read)
- {
- off_t nonzeros_needed = not_yet_read + bufsize;
- off_t full_blocks = nonzeros_needed / ST_NBLOCKSIZE;
- int partial_block = 0 < nonzeros_needed % ST_NBLOCKSIZE;
- if (ST_NBLOCKS (*st) < full_blocks + partial_block)
- return 1;
- }
- }
-
/* Look for a hole after the current location. */
- if (SEEK_HOLE != SEEK_END)
+ off_t hole_start = lseek (fd, cur, SEEK_HOLE);
+ if (0 <= hole_start)
{
- off_t hole_start = lseek (fd, cur, SEEK_HOLE);
- if (0 <= hole_start)
- {
- if (lseek (fd, cur, SEEK_SET) < 0)
- suppressible_error (filename, errno);
- if (hole_start < st->st_size)
- return 1;
- }
+ if (lseek (fd, cur, SEEK_SET) < 0)
+ suppressible_error (filename, errno);
+ if (hole_start < st->st_size)
+ return 1;
}
}
--
1.7.6.5