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Fix realpath(name, NULL) when PSEUDO_DISABLED=1

On some Linux systems, dlsym("realpath", RTLD_NEXT) prefers
for reasons of its own to give a symbol that is also known
as old_realpath, which fails and yields EINVAL when called
with a null pointer as the second argument.  This can be
avoided, on some systems, by using dlvsym() to request
the GLIBC_2.3 version of the symbol.

The wrapper logic is enhanced to allow for specifying
versions, although this currently only works for Linux
(Darwin has no dlvsym, apparently?).  The test case is
a trivial program which calls realpath(name, NULL) run
with PSEUDO_DISABLED=1.
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1 parent 1d3e67c commit c2f7c5ad8ef0f9c94a2a8382c109c8c6e16c8b18 @wr-seebs wr-seebs committed Jun 9, 2011
Showing with 52 additions and 28 deletions.
  1. +5 −0 ChangeLog.txt
  2. +1 −0 makewrappers
  3. +1 −1 ports/unix/wrapfuncs.in
  4. +37 −23 pseudo_wrappers.c
  5. +8 −4 templates/wrapper_table
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@@ -1,3 +1,8 @@
+2011-06-08:
+ * (seebs) Get the modern realpath from glibc instead of the old
+ one inexplicably proferred by RTLD_NEXT. Fixes realpath(path, NULL)
+ when PSEUDO_DISABLED=1.
+
2011-06-06:
* (seebs) revise system() handler substantially. It now
pollutes the environment but works.
View
@@ -211,6 +211,7 @@ class Function:
self.flags = '0'
self.port = port
self.directory = ''
+ self.version = 'NULL'
# On Darwin, some functions are SECRETLY converted to foo$INODE64
# when called. So we have to look those up for real_*
self.inode64 = None
View
@@ -18,7 +18,7 @@ int lutimes(const char *path, const struct timeval *tv);
char *mkdtemp(char *template);
char *mktemp(char *template);
long pathconf(const char *path, int name);
-char *realpath(const char *name, char *resolved_name);
+char *realpath(const char *name, char *resolved_name); /* version="GLIBC_2.3" */
int remove(const char *path); /* flags=AT_SYMLINK_NOFOLLOW */
DIR *opendir(const char *path);
char *tempnam(const char *template, const char *pfx);
View
@@ -90,6 +90,42 @@ pseudo_reinit_libpseudo(void) {
_libpseudo_init();
}
+static void
+pseudo_init_one_wrapper(pseudo_function *func) {
+ int (*f)(void);
+ char *e;
+ if (*func->real != NULL) {
+ /* already initialized */
+ return;
+ }
+ dlerror();
+
+#if PSEUDO_PORT_LINUX
+ if (func->version)
+ f = dlvsym(RTLD_NEXT, func->name, func->version);
+ /* fall through to the general case, if that failed */
+ if (!f)
+#endif
+ f = dlsym(RTLD_NEXT, func->name);
+ if (f) {
+ *func->real = f;
+ } else {
+ e = dlerror();
+#ifdef PSEUDO_NO_REAL_AT_FUNCTIONS
+ char *s = func->name;
+ s += strlen(s) - 2;
+ /* *at() don't have to exist */
+ if (!strcmp(s, "at")) {
+ continue;
+ }
+#else
+ if (e != NULL) {
+ pseudo_diag("No real function for %s: %s\n", func->name, e);
+ }
+#endif
+ }
+}
+
void
pseudo_init_wrappers(void) {
int i;
@@ -103,29 +139,7 @@ pseudo_init_wrappers(void) {
*/
if (!done) {
for (i = 0; pseudo_functions[i].name; ++i) {
- if (*pseudo_functions[i].real == NULL) {
- int (*f)(void);
- char *e;
- dlerror();
- f = dlsym(RTLD_NEXT, pseudo_functions[i].name);
- if (f) {
- *pseudo_functions[i].real = f;
- } else {
- e = dlerror();
-#ifdef PSEUDO_NO_REAL_AT_FUNCTIONS
- char *s = pseudo_functions[i].name;
- s += strlen(s) - 2;
- /* *at() don't have to exist */
- if (!strcmp(s, "at")) {
- continue;
- }
-#else
- if (e != NULL) {
- pseudo_diag("No real function for %s: %s\n", pseudo_functions[i].name, e);
- }
-#endif
- }
- }
+ pseudo_init_one_wrapper(&pseudo_functions[i]);
}
done = 1;
}
View
@@ -4,17 +4,21 @@
/* This file is generated and should not be modified. See the makewrappers
* script if you want to modify this. */
-static struct {
+typedef struct {
char *name; /* the name */
int (**real)(void); /* the underlying syscall */
int (*wrapper)(void); /* the wrapper from guts/name.c */
-} pseudo_functions[] = {
+ char *version; /* the version, if we know and care */
+} pseudo_function;
+
+static pseudo_function pseudo_functions[] = {
@body
{ /* ${comment}; */
"${name}${maybe_inode64}",
(int (**)(void)) &real_${name},
- (int (*)(void)) wrap_${name}
+ (int (*)(void)) wrap_${name},
+ ${version}
},
@footer
- { NULL, NULL, NULL },
+ { NULL, NULL, NULL, NULL },
};

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