I did this:
> 2017-09-26 Bruno Haible <br...@clisp.org>
>
> vma-iter: Improvements for Linux and BSD platforms.
> - Add support for DragonFly BSD.
> - Make it more reliable on Linux, GNU/kFreeBSD, FreeBSD, NetBSD.
> * lib/vma-iter.c (struct rofile, rof_open, rof_peekchar, rof_close):
> Read the entire file into memory in a single system call.
> (vma_iterate): Update. Read from /proc on DragonFly BSD like on FreeBSD.
> * lib/vma-iter.h (VMA_ITERATE_SUPPORTED): Define also on DragonFly BSD.
But on Linux (and not on the BSD systems), this has the effect that
vma_iterate() produces a truncated list of VMAs. This fixes it.
2017-10-07 Bruno Haible <br...@clisp.org>
vma-iter: Fix truncated result on Linux (regression from 2017-09-26).
* lib/vma-iter.c (MIN_LEFTOVER): New macro.
(STACK_ALLOCATED_BUFFER_SIZE): Set to a minimal value if not needed.
(rof_open): On Linux, do multiple read() calls and make sure
MIN_LEFTOVER bytes are left when read() returns.
>From 7f56e496c731f8da732d5a3cc2afddad86cda5be Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sat, 7 Oct 2017 14:07:41 +0200
Subject: [PATCH] vma-iter: Fix truncated result on Linux (regression from
2017-09-26).
* lib/vma-iter.c (MIN_LEFTOVER): New macro.
(STACK_ALLOCATED_BUFFER_SIZE): Set to a minimal value if not needed.
(rof_open): On Linux, do multiple read() calls and make sure
MIN_LEFTOVER bytes are left when read() returns.
---
ChangeLog | 8 ++++++
lib/vma-iter.c | 87 ++++++++++++++++++++++++++++++++++++++++++++--------------
2 files changed, 74 insertions(+), 21 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 894c3c6..74d1d1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
2017-10-07 Bruno Haible <br...@clisp.org>
+ vma-iter: Fix truncated result on Linux (regression from 2017-09-26).
+ * lib/vma-iter.c (MIN_LEFTOVER): New macro.
+ (STACK_ALLOCATED_BUFFER_SIZE): Set to a minimal value if not needed.
+ (rof_open): On Linux, do multiple read() calls and make sure
+ MIN_LEFTOVER bytes are left when read() returns.
+
+2017-10-07 Bruno Haible <br...@clisp.org>
+
vma-iter: Improve support for GNU/Hurd.
* lib/vma-iter.c (vma_iterate): On GNU/Hurd, use the Mach vm_region()
API, not the /proc file system.
diff --git a/lib/vma-iter.c b/lib/vma-iter.c
index 0fb8834..2666940 100644
--- a/lib/vma-iter.c
+++ b/lib/vma-iter.c
@@ -34,6 +34,10 @@
#include <fcntl.h> /* open, O_RDONLY */
#include <unistd.h> /* getpagesize, lseek, read, close, getpid */
+#if defined __linux__
+# include <limits.h> /* PATH_MAX */
+#endif
+
#if defined __linux__ || defined __FreeBSD_kernel__ || defined __FreeBSD__ || defined __DragonFly__ || defined __NetBSD__ /* || defined __CYGWIN__ */
# include <sys/types.h>
# include <sys/mman.h> /* mmap, munmap */
@@ -116,11 +120,27 @@
VMAs with nonsensical addresses.
So use mmap(), and ignore the resulting VMA. */
+# ifdef __linux__
+ /* On Linux, if the file does not entirely fit into the buffer, the read()
+ function stops before the line that would come out truncated. The
+ maximum size of such a line is 73 + PATH_MAX bytes. To be sure that we
+ have read everything, we must verify that at least that many bytes are
+ left when read() returned. */
+# define MIN_LEFTOVER (73 + PATH_MAX)
+# else
+# define MIN_LEFTOVER 0
+# endif
+
# ifdef TEST
/* During testing, we want to run into the hairy cases. */
# define STACK_ALLOCATED_BUFFER_SIZE 32
# else
-# define STACK_ALLOCATED_BUFFER_SIZE 1024
+# if MIN_LEFTOVER < 1024
+# define STACK_ALLOCATED_BUFFER_SIZE 1024
+# else
+ /* There is no point in using a stack-allocated buffer if it is too small anyway. */
+# define STACK_ALLOCATED_BUFFER_SIZE 1
+# endif
# endif
struct rofile
@@ -160,33 +180,58 @@ rof_open (struct rofile *rof, const char *filename)
for (;;)
{
/* Attempt to read the contents in a single system call. */
- {
- int n = read (fd, rof->buffer, size);
-# ifdef EINTR
- if (n < 0 && errno == EINTR)
- goto retry;
-# endif
+ if (size > MIN_LEFTOVER)
+ {
+ int n = read (fd, rof->buffer, size);
+ if (n < 0 && errno == EINTR)
+ goto retry;
# if defined __DragonFly__
- if (!(n < 0 && errno == EFBIG))
+ if (!(n < 0 && errno == EFBIG))
# endif
- {
- if (n <= 0)
- /* Empty file. */
- goto fail1;
- if (n < size)
- {
- /* The buffer was sufficiently large. */
- rof->filled = n;
- close (fd);
- return 0;
- }
- }
- }
+ {
+ if (n <= 0)
+ /* Empty file. */
+ goto fail1;
+ if (n + MIN_LEFTOVER <= size)
+ {
+ /* The buffer was sufficiently large. */
+ rof->filled = n;
+# ifdef __linux__
+ /* On Linux, the read() call may stop even if the buffer was
+ large enough. We need the equivalent of full_read(). */
+ for (;;)
+ {
+ n = read (fd, rof->buffer + rof->filled, size - rof->filled);
+ if (n < 0 && errno == EINTR)
+ goto retry;
+ if (n < 0)
+ /* Some error. */
+ goto fail1;
+ if (n + MIN_LEFTOVER > size - rof->filled)
+ /* Allocate a larger buffer. */
+ break;
+ if (n == 0)
+ {
+ /* Reached the end of file. */
+ close (fd);
+ return 0;
+ }
+ rof->filled += n;
+ }
+# else
+ close (fd);
+ return 0;
+# endif
+ }
+ }
+ }
/* Allocate a larger buffer. */
if (pagesize == 0)
{
pagesize = getpagesize ();
size = pagesize;
+ while (size <= MIN_LEFTOVER)
+ size = 2 * size;
}
else
{
--
2.7.4
