diff --no-dereference causes diff to not follow symlinks, instead comparing
the link name.
Added some basic tests.
---
lib/lib.h | 1 +
lib/xwrap.c | 5 +++
tests/diff.test | 7 ++++
toys/pending/diff.c | 96 +++++++++++++++++++++++++++++++++++----------
4 files changed, 88 insertions(+), 21 deletions(-)
From 70b83f76997297b91c11813813989bc07b42739b Mon Sep 17 00:00:00 2001
From: Daniel Rosenberg <dro...@google.com>
Date: Tue, 30 Jul 2024 18:05:26 -0700
Subject: [PATCH] Support diff --no-dereference
diff --no-dereference causes diff to not follow symlinks, instead comparing
the link name.
Added some basic tests.
---
lib/lib.h | 1 +
lib/xwrap.c | 5 +++
tests/diff.test | 7 ++++
toys/pending/diff.c | 96 +++++++++++++++++++++++++++++++++++----------
4 files changed, 88 insertions(+), 21 deletions(-)
diff --git a/lib/lib.h b/lib/lib.h
index 23b1e680..167bed59 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -156,6 +156,7 @@ char *xreadfile(char *name, char *buf, off_t len);
int xioctl(int fd, int request, void *data);
char *xgetcwd(void);
void xstat(char *path, struct stat *st);
+void xlstat(char *path, struct stat *st);
char *xabspath(char *path, int exact);
void xchdir(char *path);
void xchroot(char *path);
diff --git a/lib/xwrap.c b/lib/xwrap.c
index d07f355a..5098553f 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -576,6 +576,11 @@ void xstat(char *path, struct stat *st)
if(stat(path, st)) perror_exit("Can't stat %s", path);
}
+void xlstat(char *path, struct stat *st)
+{
+ if(lstat(path, st)) perror_exit("Can't lstat %s", path);
+}
+
// Canonicalize path, even to file with one or more missing components at end.
// Returns allocated string for pathname or NULL if doesn't exist. Flags are:
// ABS_PATH:path to last component must exist ABS_FILE: whole path must exist
diff --git a/tests/diff.test b/tests/diff.test
index 9361a41e..8c5834d3 100644
--- a/tests/diff.test
+++ b/tests/diff.test
@@ -43,6 +43,13 @@ echo -e "1\n3" > bb
testcmd "line format" "--unchanged-line-format=U%l --old-line-format=D%l --new-line-format=A%l aa bb" "U1D2A3" "" ""
testcmd "line format empty" "--unchanged-line-format= --old-line-format=D%l --new-line-format=A%l aa bb" "D2A3" "" ""
+ln -s aa cc
+testcmd "follow symlink" "-q -L aa -L cc aa cc" "" "" ""
+testcmd "no follow symlink" "-q --no-dereference -L aa -L cc aa cc" "File aa is a regular file while file cc is a symbolic link\n" "" ""
+ln -s ./aa dd
+testcmd "symlink differs" "-q -L cc -L dd cc dd" "" "" ""
+testcmd "symlink differs no follow" "-q --no-dereference -L cc -L dd cc dd" "Symbolic links cc and dd differ\n" "" ""
+
mkfifo fifo1
mkfifo fifo2
echo -e "1\n2" > fifo1&
diff --git a/toys/pending/diff.c b/toys/pending/diff.c
index 27873cfd..34bba904 100644
--- a/toys/pending/diff.c
+++ b/toys/pending/diff.c
@@ -8,7 +8,7 @@
*
* Deviations from posix: always does -u
-USE_DIFF(NEWTOY(diff, "<2>2(unchanged-line-format):;(old-line-format):;(new-line-format):;(color)(strip-trailing-cr)B(ignore-blank-lines)d(minimal)b(ignore-space-change)ut(expand-tabs)w(ignore-all-space)i(ignore-case)T(initial-tab)s(report-identical-files)q(brief)a(text)S(starting-file):F(show-function-line):;L(label)*N(new-file)r(recursive)U(unified)#<0=3", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_ARGFAIL(2)))
+USE_DIFF(NEWTOY(diff, "<2>2(unchanged-line-format):;(old-line-format):;(no-dereference);(new-line-format):;(color)(strip-trailing-cr)B(ignore-blank-lines)d(minimal)b(ignore-space-change)ut(expand-tabs)w(ignore-all-space)i(ignore-case)T(initial-tab)s(report-identical-files)q(brief)a(text)S(starting-file):F(show-function-line):;L(label)*N(new-file)r(recursive)U(unified)#<0=3", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_ARGFAIL(2)))
config DIFF
bool "diff"
@@ -35,6 +35,7 @@ config DIFF
-w Ignore all whitespace
--color Color output --strip-trailing-cr Strip '\r' from input lines
+ --no-dereference Don't follow symbolic links
--TYPE-line-format=FORMAT Display TYPE (unchanged/old/new) lines using FORMAT
FORMAT uses printf integer escapes (ala %-2.4x) followed by LETTER: FELMNn
Supported format specifiers are:
@@ -51,7 +52,7 @@ GLOBALS(
struct arg_list *L;
char *F, *S, *new_line_format, *old_line_format, *unchanged_line_format;
- int dir_num, size, is_binary, differ, change, len[2], *offset[2];
+ int dir_num, size, is_binary, is_symlink, differ, change, len[2], *offset[2];
struct stat st[2];
struct {
char **list;
@@ -61,6 +62,10 @@ GLOBALS(
FILE *fp;
int len;
} file[2];
+ struct {
+ char *name;
+ int len;
+ } link[2];
)
#define IS_STDIN(s) (*(s)=='-' && !(s)[1])
@@ -512,19 +517,19 @@ static int list_dir(struct dirtree *node)
if (S_ISDIR(node->st.st_mode) && !node->parent) { //add root dirs.
add_to_list(node);
- return (DIRTREE_RECURSE|DIRTREE_SYMFOLLOW);
+ return (DIRTREE_RECURSE|((FLAG(no_dereference)) ? 0 : DIRTREE_SYMFOLLOW));
}
if (S_ISDIR(node->st.st_mode) && FLAG(r)) {
if (!FLAG(N)) ret = skip(node);
- if (!ret) return DIRTREE_RECURSE|DIRTREE_SYMFOLLOW;
+ if (!ret) return DIRTREE_RECURSE|((FLAG(no_dereference)) ? 0 : DIRTREE_SYMFOLLOW);
else {
add_to_list(node); //only at one side.
return 0;
}
} else {
add_to_list(node);
- return S_ISDIR(node->st.st_mode) ? 0 : (DIRTREE_RECURSE|DIRTREE_SYMFOLLOW);
+ return S_ISDIR(node->st.st_mode) ? 0 : (DIRTREE_RECURSE|((FLAG(no_dereference)) ? 0 : DIRTREE_SYMFOLLOW));
}
}
@@ -578,6 +583,32 @@ static void show_label(char *prefix, char *filename, struct stat *sb)
free(quoted_file);
}
+static void do_symlink_diff(char **files)
+{
+ size_t i;
+ int s = sizeof(toybuf)/2;
+
+ TT.is_symlink = 1;
+ for (i = 0; i < 2; i++) {
+ TT.link[i].name = toybuf + i * s;
+ TT.link[i].len = readlink0(files[i], TT.link[i].name, s);
+ if (TT.link[i].len == 0) {
+ perror_msg("readlink failed");
+ TT.differ = 2;
+ return;
+ }
+ }
+
+ if (TT.link[0].len != TT.link[1].len) {
+ TT.differ = 1;
+ return;
+ }
+
+ if (smemcmp(TT.link[0].name, TT.link[1].name, TT.link[0].len))
+ TT.differ = 1;
+ return;
+}
+
static void do_diff(char **files)
{
long i = 1, size = 1, x = 0, change = 0, ignore_white,
@@ -717,9 +748,9 @@ calc_ct:
static void show_status(char **files)
{
if (TT.differ==2) return; // TODO: needed?
- if (TT.differ ? FLAG(q) || TT.is_binary : FLAG(s))
- printf("Files %s and %s %s\n", files[0], files[1],
- TT.differ ? "differ" : "are identical");
+ if (TT.differ ? FLAG(q) || TT.is_binary || TT.is_symlink : FLAG(s))
+ printf("%s %s and %s %s\n", TT.is_symlink ? "Symbolic links" : "Files",
+ files[0], files[1], TT.differ ? "differ" : "are identical");
}
static void create_empty_entry(int l , int r, int j)
@@ -736,25 +767,33 @@ static void create_empty_entry(int l , int r, int j)
f[!i] = "/dev/null";
}
path[i] = f[i] = TT.dir[i].list[i ? r : l];
- stat(f[i], st+i);
+ if (FLAG(no_dereference))
+ lstat(f[i], st+i);
+ else
+ stat(f[i], st+i);
if (j) st[!i] = st[i];
}
for (i = 0; i<2; i++) {
- if (!S_ISREG(st[i].st_mode) && !S_ISDIR(st[i].st_mode)) {
- printf("File %s is not a regular file or directory and was skipped\n",
+ if (!S_ISREG(st[i].st_mode) && !S_ISDIR(st[i].st_mode) && !S_ISLNK(st[i].st_mode)) {
+ printf("File %s is not a regular file, symbolic link, or directory and was skipped\n",
path[i]);
break;
}
}
if (i != 2);
- else if (S_ISDIR(st[0].st_mode) && S_ISDIR(st[1].st_mode))
- printf("Common subdirectories: %s and %s\n", path[0], path[1]);
- else if ((i = S_ISDIR(st[0].st_mode)) != S_ISDIR(st[1].st_mode)) {
- char *fidir[] = {"directory", "regular file"};
+ else if ((st[0].st_mode & S_IFMT) != (st[1].st_mode & S_IFMT)) {
+ i = S_ISREG(st[0].st_mode) + 2 * S_ISLNK(st[0].st_mode);
+ int k = S_ISREG(st[1].st_mode) + 2 * S_ISLNK(st[1].st_mode);
+ char *fidir[] = {"directory", "regular file", "symbolic link"};
printf("File %s is a %s while file %s is a %s\n",
- path[0], fidir[!i], path[1], fidir[i]);
+ path[0], fidir[i], path[1], fidir[k]);
+ } else if (S_ISDIR(st[0].st_mode))
+ printf("Common subdirectories: %s and %s\n", path[0], path[1]);
+ else if (S_ISLNK(st[0].st_mode)) {
+ do_symlink_diff(f);
+ show_status(path);
} else {
do_diff(f);
show_status(path);
@@ -814,14 +853,17 @@ static void diff_dir(int *start)
void diff_main(void)
{
- int j = 0, k = 1, start[2] = {1, 1};
+ int i, j = 0, k = 1, start[2] = {1, 1};
char **files = toys.optargs;
toys.exitval = 2;
if (FLAG(color) && !isatty(1)) toys.optflags ^= FLAG_color;
for (j = 0; j < 2; j++) {
+ {
+ }
if (IS_STDIN(files[j])) fstat(0, &TT.st[j]);
+ else if (FLAG(no_dereference)) xlstat(files[j], &TT.st[j]);
else xstat(files[j], &TT.st[j]);
}
@@ -844,7 +886,7 @@ void diff_main(void)
if (S_ISDIR(TT.st[0].st_mode) && S_ISDIR(TT.st[1].st_mode)) {
for (j = 0; j < 2; j++) {
memset(TT.dir+j, 0, sizeof(*TT.dir));
- dirtree_flagread(files[j], DIRTREE_SYMFOLLOW, list_dir);
+ dirtree_flagread(files[j], (FLAG(no_dereference)) ? 0 : DIRTREE_SYMFOLLOW, list_dir);
TT.dir[j].nr_elm = TT.size; //size updated in list_dir
qsort(&TT.dir[j].list[1], TT.size-1, sizeof(char *), (void *)cmp);
@@ -868,10 +910,22 @@ void diff_main(void)
char *slash = strrchr(files[d], '/');
files[!d] = concat_file_path(files[!d], slash ? slash+1 : files[d]);
- if (stat(files[!d], &TT.st[!d])) perror_exit("%s", files[!d]);
+ if (FLAG(no_dereference)) {
+ if (lstat(files[!d], &TT.st[!d])) perror_exit("%s", files[!d]);
+ } else {
+ if (stat(files[!d], &TT.st[!d])) perror_exit("%s", files[!d]);
+ }
+ }
+ if ((i = S_ISREG(TT.st[0].st_mode)) != S_ISREG(TT.st[1].st_mode)) {
+ char *fidir[] = {"regular file", "symbolic link"};
+ printf("File %s is a %s while file %s is a %s\n",
+ files[0], fidir[!i], files[1], fidir[i]);
+ TT.differ = 1;
+ } else {
+ if (S_ISLNK(TT.st[0].st_mode)) do_symlink_diff(files);
+ else do_diff(files);
+ show_status(files);
}
- do_diff(files);
- show_status(files);
if (TT.file[0].fp) fclose(TT.file[0].fp);
if (TT.file[1].fp) fclose(TT.file[1].fp);
}
base-commit: 0b2d5c2bb3f198acda0b340ec0e5be4ae75b7914
--
2.46.0.76.ge559c4bf1a-goog
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