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authorJim Meyering <meyering@redhat.com>2011-10-18 11:44:39 +0200
committerJim Meyering <meyering@redhat.com>2011-10-19 09:31:30 +0200
commitd96c2069d9453ba455540e045046ead19e885ff7 (patch)
tree5e63b9f92f45b53abf11f53cfbeef899953946c2
parent385634c8dd512fc4fae46310266247b8fcf2a85a (diff)
downloadcoreutils-d96c2069d9453ba455540e045046ead19e885ff7.tar.xz
tac: use only one temporary file, with multiple nonseekable inputs
* src/tac.c (temp_stream): New function, factored out of... (copy_to_temp): ...here. (tac_nonseekable): Don't free or fclose, now that we reuse the file. Suggested by Ambrose Feinstein. * THANKS.in: Update.
-rw-r--r--THANKS.in1
-rw-r--r--src/tac.c120
2 files changed, 72 insertions, 49 deletions
diff --git a/THANKS.in b/THANKS.in
index 23ac67920..83a78649a 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -37,6 +37,7 @@ Alexandre Duret-Lutz duret_g@epita.fr
Alexey Solovyov alekso@math.uu.se
Alexey Vyskubov alexey@pippuri.mawhrin.net
Alfred M. Szmidt ams@kemisten.nu
+Ambrose Feinstein ambrose@google.com
Andi Kleen freitag@alancoxonachip.com
Andre Novaes Cunha Andre.Cunha@br.global-one.net
Andreas Frische andreasfrische@gmail.com
diff --git a/src/tac.c b/src/tac.c
index 7d99595e2..6a7e51081 100644
--- a/src/tac.c
+++ b/src/tac.c
@@ -418,53 +418,78 @@ record_or_unlink_tempfile (char const *fn, FILE *fp ATTRIBUTE_UNUSED)
#endif
-/* Copy from file descriptor INPUT_FD (corresponding to the named FILE) to
- a temporary file, and set *G_TMP and *G_TEMPFILE to the resulting stream
- and file name. Return true if successful. */
-
+/* A wrapper around mkstemp that gives us both an open stream pointer,
+ FP, and the corresponding FILE_NAME. Always return the same FP/name
+ pair, rewinding/truncating it upon each reuse. */
static bool
-copy_to_temp (FILE **g_tmp, char **g_tempfile, int input_fd, char const *file)
+temp_stream (FILE **fp, char **file_name)
{
- static char *template = NULL;
- static char const *tempdir;
-
- if (template == NULL)
+ static char *tempfile = NULL;
+ static FILE *tmp_fp;
+ if (tempfile == NULL)
{
- char *t = getenv ("TMPDIR");
- tempdir = t ? t : DEFAULT_TMPDIR;
- template = file_name_concat (tempdir, "tacXXXXXX", NULL);
- }
+ char const *t = getenv ("TMPDIR");
+ char const *tempdir = t ? t : DEFAULT_TMPDIR;
+ tempfile = file_name_concat (tempdir, "tacXXXXXX", NULL);
+
+ /* FIXME: there's a small window between a successful mkstemp call
+ and the unlink that's performed by record_or_unlink_tempfile.
+ If we're interrupted in that interval, this code fails to remove
+ the temporary file. On systems that define DONT_UNLINK_WHILE_OPEN,
+ the window is much larger -- it extends to the atexit-called
+ unlink_tempfile.
+ FIXME: clean up upon fatal signal. Don't block them, in case
+ $TMPFILE is a remote file system. */
+
+ int fd = mkstemp (tempfile);
+ if (fd < 0)
+ {
+ error (0, errno, _("cannot create temporary file in %s"),
+ quote (tempdir));
+ goto Reset;
+ }
- /* FIXME: there's a small window between a successful mkstemp call
- and the unlink that's performed by record_or_unlink_tempfile.
- If we're interrupted in that interval, this code fails to remove
- the temporary file. On systems that define DONT_UNLINK_WHILE_OPEN,
- the window is much larger -- it extends to the atexit-called
- unlink_tempfile.
- FIXME: clean up upon fatal signal. Don't block them, in case
- $TMPFILE is a remote file system. */
-
- char *tempfile = xstrdup (template);
- int fd = mkstemp (tempfile);
- if (fd < 0)
- {
- error (0, errno, _("cannot create temporary file in %s"),
- quote (tempdir));
- free (tempfile);
- return false;
- }
+ tmp_fp = fdopen (fd, (O_BINARY ? "w+b" : "w+"));
+ if (! tmp_fp)
+ {
+ error (0, errno, _("cannot open %s for writing"), quote (tempfile));
+ close (fd);
+ unlink (tempfile);
+ Reset:
+ free (tempfile);
+ tempfile = NULL;
+ return false;
+ }
- FILE *tmp = fdopen (fd, (O_BINARY ? "w+b" : "w+"));
- if (! tmp)
+ record_or_unlink_tempfile (tempfile, tmp_fp);
+ }
+ else
{
- error (0, errno, _("cannot open %s for writing"), quote (tempfile));
- close (fd);
- unlink (tempfile);
- free (tempfile);
- return false;
+ if (fseek (tmp_fp, 0, SEEK_SET) < 0
+ || ftruncate (fileno (tmp_fp), 0) < 0)
+ {
+ error (0, errno, _("failed to rewind stream for %s"),
+ quote (tempfile));
+ return false;
+ }
}
- record_or_unlink_tempfile (tempfile, tmp);
+ *fp = tmp_fp;
+ *file_name = tempfile;
+ return true;
+}
+
+/* Copy from file descriptor INPUT_FD (corresponding to the named FILE) to
+ a temporary file, and set *G_TMP and *G_TEMPFILE to the resulting stream
+ and file name. Return true if successful. */
+
+static bool
+copy_to_temp (FILE **g_tmp, char **g_tempfile, int input_fd, char const *file)
+{
+ FILE *fp;
+ char *file_name;
+ if (!temp_stream (&fp, &file_name))
+ return false;
while (1)
{
@@ -477,26 +502,25 @@ copy_to_temp (FILE **g_tmp, char **g_tempfile, int input_fd, char const *file)
goto Fail;
}
- if (fwrite (G_buffer, 1, bytes_read, tmp) != bytes_read)
+ if (fwrite (G_buffer, 1, bytes_read, fp) != bytes_read)
{
- error (0, errno, _("%s: write error"), quotearg_colon (tempfile));
+ error (0, errno, _("%s: write error"), quotearg_colon (file_name));
goto Fail;
}
}
- if (fflush (tmp) != 0)
+ if (fflush (fp) != 0)
{
- error (0, errno, _("%s: write error"), quotearg_colon (tempfile));
+ error (0, errno, _("%s: write error"), quotearg_colon (file_name));
goto Fail;
}
- *g_tmp = tmp;
- *g_tempfile = tempfile;
+ *g_tmp = fp;
+ *g_tempfile = file_name;
return true;
Fail:
- fclose (tmp);
- free (tempfile);
+ fclose (fp);
return false;
}
@@ -512,8 +536,6 @@ tac_nonseekable (int input_fd, const char *file)
return false;
bool ok = tac_seekable (fileno (tmp_stream), tmp_file);
- fclose (tmp_stream);
- free (tmp_file);
return ok;
}