82 lines
2.9 KiB
Diff
82 lines
2.9 KiB
Diff
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From 7386c291be8e2de115f2e161886e872429edadd7 Mon Sep 17 00:00:00 2001
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From: Paul Eggert <eggert@cs.ucla.edu>
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Date: Fri, 14 Feb 2025 13:10:02 -0800
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Subject: =?UTF-8?q?cat:=20fix=20plain=20=E2=80=98cat=E2=80=99=20bug?=
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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* src/cat.c (main): Do not fail with plain ‘cat’ where input and
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output are both /dev/tty, if the output happens to have O_APPEND set.
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Problem reported by lilydjwg <https://bugs.gnu.org/76255>.
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Also, don’t report an error if the seek position is at or after EOF,
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even if O_APPEND is set.
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---
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src/cat.c | 26 +++++++++++++-------------
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1 file changed, 13 insertions(+), 13 deletions(-)
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(limited to 'src/cat.c')
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diff --git a/src/cat.c b/src/cat.c
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index 274f844..c022103 100644
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--- a/src/cat.c
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+++ b/src/cat.c
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@@ -646,9 +646,15 @@
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idx_t outsize = io_blksize (stat_buf);
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/* Device, I-node number and lazily-acquired flags of the output. */
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- dev_t out_dev = stat_buf.st_dev;
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- ino_t out_ino = stat_buf.st_ino;
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+ dev_t out_dev;
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+ ino_t out_ino;
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int out_flags = -2;
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+ bool have_out_dev = ! (S_TYPEISSHM (&stat_buf) || S_TYPEISTMO (&stat_buf));
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+ if (have_out_dev)
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+ {
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+ out_dev = stat_buf.st_dev;
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+ out_ino = stat_buf.st_ino;
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+ }
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/* True if the output is a regular file. */
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bool out_isreg = S_ISREG (stat_buf.st_mode) != 0;
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@@ -706,22 +712,25 @@
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output device. It's better to catch this error earlier
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rather than later. */
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- if (stat_buf.st_dev == out_dev && stat_buf.st_ino == out_ino)
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+ if (! (S_ISFIFO (stat_buf.st_mode) || S_ISSOCK (stat_buf.st_mode)
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+ || S_TYPEISSHM (&stat_buf) || S_TYPEISTMO (&stat_buf))
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+ && have_out_dev
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+ && stat_buf.st_dev == out_dev && stat_buf.st_ino == out_ino)
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{
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- if (out_flags < -1)
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- out_flags = fcntl (STDOUT_FILENO, F_GETFL);
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- bool exhausting = 0 <= out_flags && out_flags & O_APPEND;
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- if (!exhausting)
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- {
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- off_t in_pos = lseek (input_desc, 0, SEEK_CUR);
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- if (0 <= in_pos)
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- exhausting = in_pos < lseek (STDOUT_FILENO, 0, SEEK_CUR);
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- }
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- if (exhausting)
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+ off_t in_pos = lseek (input_desc, 0, SEEK_CUR);
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+ if (0 <= in_pos)
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{
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- error (0, 0, _("%s: input file is output file"), quotef (infile));
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- ok = false;
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- goto contin;
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+ if (out_flags < -1)
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+ out_flags = fcntl (STDOUT_FILENO, F_GETFL);
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+ int whence = (0 <= out_flags && out_flags & O_APPEND
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+ ? SEEK_END : SEEK_CUR);
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+ if (in_pos < lseek (STDOUT_FILENO, 0, whence))
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+ {
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+ error (0, 0, _("%s: input file is output file"),
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+ quotef (infile));
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+ ok = false;
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+ goto contin;
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+ }
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}
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}
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