[114096] trunk/base/src/darwintracelib1.0/darwintrace.c
cal at macports.org
cal at macports.org
Thu Nov 28 18:11:12 PST 2013
Revision: 114096
https://trac.macports.org/changeset/114096
Author: cal at macports.org
Date: 2013-11-28 18:11:12 -0800 (Thu, 28 Nov 2013)
Log Message:
-----------
darwintrace: fix expansion of multiple symlinks
Expanding a series of symlinks longer than a single symlink would previously
lead to re-use of a buffer that was used to store the result of readlink(2)
while the contents of the buffer were still in use in the pathComponent array.
This change refactors the path parsing and handling completely such that the
components of the normalized path will always be stored in the same buffer (and
other components will be copied there when needed), avoiding this problem.
Fixes the configure phase of stellarium and automoc (if you don't have
DARWINTRACE_DEBUG enabled).
Modified Paths:
--------------
trunk/base/src/darwintracelib1.0/darwintrace.c
Modified: trunk/base/src/darwintracelib1.0/darwintrace.c
===================================================================
--- trunk/base/src/darwintracelib1.0/darwintrace.c 2013-11-29 02:06:55 UTC (rev 114095)
+++ trunk/base/src/darwintracelib1.0/darwintrace.c 2013-11-29 02:11:12 UTC (rev 114096)
@@ -707,90 +707,140 @@
return true;
}
- char *pathComponents[MAXPATHLEN / 2 + 2];
- size_t componentIdx = 0;
+ typedef struct {
+ char *start;
+ size_t len;
+ } path_component_t;
+ char normPath[MAXPATHLEN];
+ normPath[0] = '/';
+ normPath[1] = '\0';
+
+ path_component_t pathComponents[MAXPATHLEN / 2 + 2];
+ size_t numComponents = 0;
+
// Make sure the path is absolute.
- char cwd[MAXPATHLEN];
- if (path == NULL) {
+ if (path == NULL || *path == '\0') {
// this is most certainly invalid, let the syscall deal with it
return true;
}
+
+ char *dst = NULL;
+ const char *token = NULL;
+ size_t idx;
if (*path != '/') {
// The path isn't absolute, start by populating pathcomponents with the
// current working directory
- if (getcwd(cwd, sizeof(cwd)) == NULL) {
+ if (getcwd(normPath, sizeof(normPath)) == NULL) {
perror("darwintrace: getcwd");
abort();
}
- char *lastToken = cwd + 1;
- char *token = NULL;
- while (NULL != (token = strsep(&lastToken, "/"))) {
- pathComponents[componentIdx++] = token;
+ char *writableToken = normPath + 1;
+ while ((idx = strcspn(writableToken, "/")) > 0) {
+ // found a token, tokenize and store it
+ pathComponents[numComponents].start = writableToken;
+ pathComponents[numComponents].len = idx;
+ numComponents++;
+
+ bool final = writableToken[idx] == '\0';
+ writableToken[idx] = '\0';
+ if (final) {
+ break;
+ }
+ // advance token
+ writableToken += idx + 1;
}
+
+ // copy path after the CWD into the buffer and normalize it
+ if (numComponents > 0) {
+ path_component_t *lastComponent = pathComponents + (numComponents - 1);
+ dst = lastComponent->start + lastComponent->len + 1;
+ } else {
+ dst = normPath + 1;
+ }
+
+ // continue parsing at the begin of path
+ token = path;
+ } else {
+ // skip leading '/'
+ dst = normPath + 1;
+ *dst = '\0';
+ token = path + 1;
}
- // Copy path to a writable buffer
- char lpath[strlen(path) + 1];
- strcpy(lpath, path);
-
/* Make sure the path is normalized. NOTE: Do _not_ use realpath(3) here.
* Doing so _will_ lead to problems. This is essentially a very simple
* re-implementation of realpath(3). */
- char *lastToken = lpath;
- char *token = NULL;
- while (NULL != (token = strsep(&lastToken, "/"))) {
- if (token[0] == '\0') {
+ while ((idx = strcspn(token, "/")) > 0) {
+ // found a token, process it
+
+ if (token[0] == '\0' || token[0] == '/') {
// empty entry, ignore
- } else if (token[0] == '.' && token[1] == '\0') {
+ } else if (token[0] == '.' && (token[1] == '\0' || token[1] == '/')) {
// reference to current directory, ignore
- } else if (token[0] == '.' && token[1] == '.' && token[2] == '\0') {
+ } else if (token[0] == '.' && token[1] == '.' && (token[2] == '\0' || token[2] == '/')) {
// walk up one directory, but not if it's the last one, because /.. -> /
- if (componentIdx > 0) {
- componentIdx--;
+ if (numComponents > 0) {
+ numComponents--;
+ if (numComponents > 0) {
+ // move dst back to the previous entry
+ path_component_t *lastComponent = pathComponents + (numComponents - 1);
+ dst = lastComponent->start + lastComponent->len + 1;
+ } else {
+ // we're at the top, move dst back to the beginning
+ dst = normPath + 1;
+ }
}
} else {
- // default case: standard path
- pathComponents[componentIdx++] = token;
+ // copy token to normPath buffer (and null-terminate it)
+ strlcpy(dst, token, idx + 1);
+ dst[idx] = '\0';
+ // add descriptor entry for new token
+ pathComponents[numComponents].start = dst;
+ pathComponents[numComponents].len = idx;
+ numComponents++;
+
+ // advance destination
+ dst += idx + 1;
}
+
+ if (token[idx] == '\0') {
+ break;
+ }
+ token += idx + 1;
}
- char link[MAXPATHLEN];
- char normPath[MAXPATHLEN];
bool pathIsSymlink;
size_t loopCount = 0;
do {
pathIsSymlink = false;
+ // Add the slashes and the terminating \0
+ for (size_t i = 0; i < numComponents; ++i) {
+ if (i == numComponents - 1) {
+ pathComponents[i].start[pathComponents[i].len] = '\0';
+ } else {
+ pathComponents[i].start[pathComponents[i].len] = '/';
+ }
+ }
+
if (++loopCount >= 10) {
// assume cylce and let the OS deal with that (yes, this actually
// happens in software!)
break;
}
- char *normPathPos = normPath;
- *normPathPos = '\0';
-
- // Build a canonical representation of the path
- for (size_t i = 0; i < componentIdx; ++i) {
- *normPathPos++ = '/';
- normPathPos = stpcpy(normPathPos, pathComponents[i]);
- }
- if (componentIdx == 0) {
- // path is "/"
- *normPathPos++ = '/';
- *normPathPos = '\0';
- }
-
// Check whether the last component is a symlink; if it is, check
// whether it is in the sandbox, expand it and do the same thing again.
struct stat st;
+ //debug_printf("checking for symlink: %s\n", normPath);
if (lstat(normPath, &st) != -1 && S_ISLNK(st.st_mode)) {
if (!__darwintrace_sandbox_check(normPath, flags)) {
return false;
}
+ char link[MAXPATHLEN];
pathIsSymlink = true;
ssize_t linksize;
@@ -799,33 +849,66 @@
abort();
}
link[linksize] = '\0';
+ //debug_printf("readlink(%s) = %s\n", normPath, link);
if (*link == '/') {
// symlink is absolute, start fresh
- componentIdx = 0;
+ numComponents = 0;
+ token = link + 1;
+ dst = normPath + 1;
} else {
// symlink is relative, remove last component
- if (componentIdx > 0) {
- componentIdx--;
+ token = link;
+ if (numComponents > 0) {
+ numComponents--;
+ if (numComponents > 0) {
+ // move dst back to the previous entry
+ path_component_t *lastComponent = pathComponents + (numComponents - 1);
+ dst = lastComponent->start + lastComponent->len + 1;
+ } else {
+ // we're at the top, move dst back to the beginning
+ dst = normPath + 1;
+ }
}
}
- lastToken = link;
- token = NULL;
- while (NULL != (token = strsep(&lastToken, "/"))) {
- if (token[0] == '\0') {
+ while ((idx = strcspn(token, "/")) > 0) {
+ // found a token, process it
+
+ if (token[0] == '\0' || token[0] == '/') {
// empty entry, ignore
- } else if (token[0] == '.' && token[1] == '\0') {
+ } else if (token[0] == '.' && (token[1] == '\0' || token[1] == '/')) {
// reference to current directory, ignore
- } else if (token[0] == '.' && token[1] == '.' && token[2] == '\0') {
+ } else if (token[0] == '.' && token[1] == '.' && (token[2] == '\0' || token[2] == '/')) {
// walk up one directory, but not if it's the last one, because /.. -> /
- if (componentIdx > 0) {
- componentIdx--;
+ if (numComponents > 0) {
+ numComponents--;
+ if (numComponents > 0) {
+ // move dst back to the previous entry
+ path_component_t *lastComponent = pathComponents + (numComponents - 1);
+ dst = lastComponent->start + lastComponent->len + 1;
+ } else {
+ // we're at the top, move dst back to the beginning
+ dst = normPath + 1;
+ }
}
} else {
- // default case: standard path
- pathComponents[componentIdx++] = token;
+ // copy token to normPath buffer
+ strlcpy(dst, token, idx + 1);
+ dst[idx] = '\0';
+ // add descriptor entry for new token
+ pathComponents[numComponents].start = dst;
+ pathComponents[numComponents].len = idx;
+ numComponents++;
+
+ // advance destination
+ dst += idx + 1;
}
+
+ if (token[idx] == '\0') {
+ break;
+ }
+ token += idx + 1;
}
}
} while (pathIsSymlink);
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