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source.c:openp: save/restore errno

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openp's return is documented as:

~~~
   If a file is found, return the descriptor.
   Otherwise, return -1, with errno set for the last name we tried to open.  */
~~~

By inspection, I noticed that there are function calls after the ones
that first set errno, and those may clobber errno.  It's safer to save
errno when see an open fail, and restore it on exit.

Tested on x86_64 Fedora 20.

gdb/ChangeLog:
2015-10-27  Pedro Alves  <palves@redhat.com>

	* source.c (openp): New local 'last_errno'.  Use it to
	save/restore errno.
This commit is contained in:
Pedro Alves 2015-10-27 16:03:24 +00:00
parent c2f2875869
commit 79b289e2d8
2 changed files with 12 additions and 0 deletions
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5
gdb/ChangeLog
View file

@ -1,3 +1,8 @@
2015-10-27 Pedro Alves <palves@redhat.com>
* source.c (openp): New local 'last_errno'. Use it to
save/restore errno.
2015-10-27 Pedro Alves <palves@redhat.com>
* psymtab.c (dump_psymtab_addrmap_1): Add casts.

7
gdb/source.c
View file

@ -746,6 +746,9 @@ openp (const char *path, int opts, const char *string,
struct cleanup *back_to;
int ix;
char *dir;
/* The errno set for the last name we tried to open (and
failed). */
int last_errno = 0;
/* The open syscall MODE parameter is not specified. */
gdb_assert ((mode & O_CREAT) == 0);
@ -786,6 +789,7 @@ openp (const char *path, int opts, const char *string,
filename = NULL;
fd = -1;
}
last_errno = errno;
if (!(opts & OPF_SEARCH_IN_PATH))
for (i = 0; string[i]; i++)
@ -808,6 +812,7 @@ openp (const char *path, int opts, const char *string,
alloclen = strlen (path) + strlen (string) + 2;
filename = (char *) alloca (alloclen);
fd = -1;
last_errno = ENOENT;
dir_vec = dirnames_to_char_ptr_vec (path);
back_to = make_cleanup_free_char_ptr_vec (dir_vec);
@ -878,6 +883,7 @@ openp (const char *path, int opts, const char *string,
fd = gdb_open_cloexec (filename, mode, 0);
if (fd >= 0)
break;
last_errno = errno;
}
}
@ -895,6 +901,7 @@ done:
*filename_opened = gdb_abspath (filename);
}
errno = last_errno;
return fd;
}