Discussion:
[PATCH] filenamecat: make base a suffix of result
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Paul Eggert
2018-01-14 21:32:38 UTC
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Raw Message
* lib/filenamecat-lgpl.c (longest_relative_suffix): Remove.
(mfile_name_concat): Always make BASE a suffix of the result, as
cp expects this. To implement this, separate with '.' instead of
'/' in some rare cases. Clarify spec to say ./BASE not BASE.
* tests/test-filenamecat.c (main): Adjust tests to match
current behavior. Check that BASE_IN_RESULT points to
a copy of BASE and is a suffix of the resultk, and that DIR
is a prefix of the result that is no longer than the prefix
indicated by BASE_IN_RESULT.
---
ChangeLog | 13 +++++++++++
lib/filenamecat-lgpl.c | 57 ++++++++++++++++++++++++------------------------
lib/filenamecat.c | 4 ++--
tests/test-filenamecat.c | 27 ++++++++++++++++++++---
4 files changed, 67 insertions(+), 34 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 13e868aca..e4801bd17 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2018-01-14 Paul Eggert <***@cs.ucla.edu>
+
+ filenamecat: make base a suffix of result
+ * lib/filenamecat-lgpl.c (longest_relative_suffix): Remove.
+ (mfile_name_concat): Always make BASE a suffix of the result, as
+ cp expects this. To implement this, separate with '.' instead of
+ '/' in some rare cases. Clarify spec to say ./BASE not BASE.
+ * tests/test-filenamecat.c (main): Adjust tests to match
+ current behavior. Check that BASE_IN_RESULT points to
+ a copy of BASE and is a suffix of the resultk, and that DIR
+ is a prefix of the result that is no longer than the prefix
+ indicated by BASE_IN_RESULT.
+
2018-01-04 Mathieu Lirzin <***@gnu.org>

update-copyright: Handle use of ©
diff --git a/lib/filenamecat-lgpl.c b/lib/filenamecat-lgpl.c
index 452d3b95d..f50ecc138 100644
--- a/lib/filenamecat-lgpl.c
+++ b/lib/filenamecat-lgpl.c
@@ -31,55 +31,54 @@
# define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
#endif

-/* Return the longest suffix of F that is a relative file name.
- If it has no such suffix, return the empty string. */
-
-static char const * _GL_ATTRIBUTE_PURE
-longest_relative_suffix (char const *f)
-{
- for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++)
- continue;
- return f;
-}
-
-/* Concatenate two file name components, DIR and ABASE, in
+/* Concatenate two file name components, DIR and BASE, in
newly-allocated storage and return the result.
The resulting file name F is such that the commands "ls F" and "(cd
- DIR; ls BASE)" refer to the same file, where BASE is ABASE with any
- file system prefixes and leading separators removed.
- Arrange for a directory separator if necessary between DIR and BASE
- in the result, removing any redundant separators.
+ DIR; ls ./BASE)" refer to the same file. If necessary, put
+ a separator between DIR and BASE in the result. Typically this
+ separator is "/", but in rare cases it might be ".".
In any case, if BASE_IN_RESULT is non-NULL, set
- *BASE_IN_RESULT to point to the copy of ABASE in the returned
- concatenation. However, if ABASE begins with more than one slash,
- set *BASE_IN_RESULT to point to the sole corresponding slash that
- is copied into the result buffer.
+ *BASE_IN_RESULT to point to the copy of BASE at the end of the
+ returned concatenation.

Return NULL if malloc fails. */

char *
-mfile_name_concat (char const *dir, char const *abase, char **base_in_result)
+mfile_name_concat (char const *dir, char const *base, char **base_in_result)
{
char const *dirbase = last_component (dir);
size_t dirbaselen = base_len (dirbase);
size_t dirlen = dirbase - dir + dirbaselen;
- size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1]));
-
- char const *base = longest_relative_suffix (abase);
size_t baselen = strlen (base);
-
- char *p_concat = malloc (dirlen + needs_separator + baselen + 1);
+ char sep = '\0';
+ if (dirbaselen)
+ {
+ /* DIR is not a file system root, so separate with / if needed. */
+ if (! ISSLASH (dir[dirlen - 1]) && ! ISSLASH (*base))
+ sep = '/';
+ }
+ else if (ISSLASH (*base))
+ {
+ /* DIR is a file system root and BASE begins with a slash, so
+ separate with ".". For example, if DIR is "/" and BASE is
+ "/foo" then return "/./foo", as "//foo" would be wrong on
+ some POSIX systems. A fancier algorithm could omit "." in
+ some cases but is not worth the trouble. */
+ sep = '.';
+ }
+
+ char *p_concat = malloc (dirlen + (sep != '\0') + baselen + 1);
char *p;

if (p_concat == NULL)
return NULL;

p = mempcpy (p_concat, dir, dirlen);
- *p = DIRECTORY_SEPARATOR;
- p += needs_separator;
+ *p = sep;
+ p += sep != '\0';

if (base_in_result)
- *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase);
+ *base_in_result = p;

p = mempcpy (p, base, baselen);
*p = '\0';
diff --git a/lib/filenamecat.c b/lib/filenamecat.c
index 5f5e24465..cad459586 100644
--- a/lib/filenamecat.c
+++ b/lib/filenamecat.c
@@ -32,9 +32,9 @@
"memory exhausted" condition and exit. */

char *
-file_name_concat (char const *dir, char const *abase, char **base_in_result)
+file_name_concat (char const *dir, char const *base, char **base_in_result)
{
- char *p = mfile_name_concat (dir, abase, base_in_result);
+ char *p = mfile_name_concat (dir, base, base_in_result);
if (p == NULL)
xalloc_die ();
return p;
diff --git a/tests/test-filenamecat.c b/tests/test-filenamecat.c
index f9f121712..17ac670da 100644
--- a/tests/test-filenamecat.c
+++ b/tests/test-filenamecat.c
@@ -22,6 +22,7 @@
#include "filenamecat.h"

#include <stdbool.h>
+#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -38,11 +39,11 @@ main (int argc _GL_UNUSED, char *argv[])
{"a", "/b", "a/b"},

{"/", "b", "/b"},
- {"/", "/b", "/b"},
- {"/", "/", "/"},
+ {"/", "/b", "/./b"}, /* This result could be shorter. */
+ {"/", "/", "/./"}, /* This result could be shorter. */
{"a", "/", "a/"}, /* this might deserve a diagnostic */
{"/a", "/", "/a/"}, /* this might deserve a diagnostic */
- {"a", "//b", "a/b"},
+ {"a", "//b", "a//b"},
{"", "a", "a"}, /* this might deserve a diagnostic */
};
unsigned int i;
@@ -53,11 +54,31 @@ main (int argc _GL_UNUSED, char *argv[])
char *base_in_result;
char const *const *t = tests[i];
char *res = file_name_concat (t[0], t[1], &base_in_result);
+ ptrdiff_t prefixlen = base_in_result - res;
+ size_t t0len = strlen (t[0]);
+ size_t reslen = strlen (res);
if (strcmp (res, t[2]) != 0)
{
fprintf (stderr, "test #%u: got %s, expected %s\n", i, res, t[2]);
fail = true;
}
+ if (strcmp (t[1], base_in_result) != 0)
+ {
+ fprintf (stderr, "test #%u: base %s != base_in_result %s\n",
+ i, t[1], base_in_result);
+ fail = true;
+ }
+ if (! (0 <= prefixlen && prefixlen <= reslen))
+ {
+ fprintf (stderr, "test #%u: base_in_result is not in result\n", i);
+ fail = true;
+ }
+ if (reslen < t0len || memcmp (res, t[0], t0len) != 0)
+ {
+ fprintf (stderr, "test #%u: %s is not a prefix of %s\n",
+ i, t[0], res);
+ fail = true;
+ }
}
exit (fail ? EXIT_FAILURE : EXIT_SUCCESS);
}
--
2.14.3
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