ldso: limited support for $ORIGIN in rpath

Handle it if it's in the beginning of the rpath entry as it
should be.

Posted to uclibc ml:
http://old.nabble.com/-PATCH-1-3--ldso%3A-limited-support-for-$ORIGIN-in-rpath-td31181219.html

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>

2 files changed, 59 insertions, 39 deletions

diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c
index 09b3aaf01..558176a55 100644
--- a/ldso/ldso/dl-elf.c
+++ b/ldso/ldso/dl-elf.c
@@ -133,53 +133,60 @@ _dl_protect_relro (struct elf_resolve *l)
  * in uClibc/ldso/util/ldd.c */
 static struct elf_resolve *
 search_for_named_library(const char *name, int secure, const char *path_list,
-	struct dyn_elf **rpnt)
+	struct dyn_elf **rpnt, const char *origin)
 {
-	char *path, *path_n, *mylibname;
+	char *mylibname;
+	const char *p, *pn;
 	struct elf_resolve *tpnt;
-	int done;
+	int plen;
 
 	if (path_list==NULL)
 		return NULL;
 
-	/* We need a writable copy of this string, but we don't
-	 * need this allocated permanently since we don't want
-	 * to leak memory, so use alloca to put path on the stack */
-	done = _dl_strlen(path_list);
-	path = alloca(done + 1);
-
 	/* another bit of local storage */
 	mylibname = alloca(2050);
 
-	_dl_memcpy(path, path_list, done+1);
-
 	/* Unlike ldd.c, don't bother to eliminate double //s */
 
 	/* Replace colons with zeros in path_list */
 	/* : at the beginning or end of path maps to CWD */
 	/* :: anywhere maps CWD */
 	/* "" maps to CWD */
-	done = 0;
-	path_n = path;
-	do {
-		if (*path == 0) {
-			*path = ':';
-			done = 1;
-		}
-		if (*path == ':') {
-			*path = 0;
-			if (*path_n)
-				_dl_strcpy(mylibname, path_n);
-			else
-				_dl_strcpy(mylibname, "."); /* Assume current dir if empty path */
-			_dl_strcat(mylibname, "/");
-			_dl_strcat(mylibname, name);
-			if ((tpnt = _dl_load_elf_shared_library(secure, rpnt, mylibname)) != NULL)
-				return tpnt;
-			path_n = path+1;
+	for (p = path_list; p != NULL; p = pn) {
+		pn = _dl_strchr(p + 1, ':');
+		if (pn != NULL) {
+			plen = pn - p;
+			pn++;
+		} else
+			plen = _dl_strlen(p);
+
+		if (plen >= 7 && _dl_memcmp(p, "$ORIGIN", 7) == 0) {
+			int olen;
+			if (secure && plen != 7)
+				continue;
+			if (origin == NULL)
+				continue;
+			for (olen = _dl_strlen(origin) - 1; olen >= 0 && origin[olen] != '/'; olen--)
+				;
+			if (olen <= 0)
+				continue;
+			_dl_memcpy(&mylibname[0], origin, olen);
+			_dl_memcpy(&mylibname[olen], p + 7, plen - 7);
+			mylibname[olen + plen - 7] = 0;
+		} else if (plen != 0) {
+			_dl_memcpy(mylibname, p, plen);
+			mylibname[plen] = 0;
+		} else {
+			_dl_strcpy(mylibname, ".");
 		}
-		path++;
-	} while (!done);
+		_dl_strcat(mylibname, "/");
+		_dl_strcat(mylibname, name);
+
+		tpnt = _dl_load_elf_shared_library(secure, rpnt, mylibname);
+		if (tpnt != NULL)
+			return tpnt;
+	}
+
 	return NULL;
 }
 
@@ -231,7 +238,8 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
 	if (pnt) {
 		pnt += (unsigned long) tpnt->dynamic_info[DT_STRTAB];
 		_dl_if_debug_dprint("\tsearching RPATH='%s'\n", pnt);
-		if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt)) != NULL)
+		if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt,
+						      tpnt->libname)) != NULL)
 			return tpnt1;
 	}
 #endif
@@ -239,7 +247,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
 	/* Check in LD_{ELF_}LIBRARY_PATH, if specified and allowed */
 	if (_dl_library_path) {
 		_dl_if_debug_dprint("\tsearching LD_LIBRARY_PATH='%s'\n", _dl_library_path);
-		if ((tpnt1 = search_for_named_library(libname, secure, _dl_library_path, rpnt)) != NULL)
+		if ((tpnt1 = search_for_named_library(libname, secure, _dl_library_path, rpnt, NULL)) != NULL)
 		{
 			return tpnt1;
 		}
@@ -253,7 +261,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
 	if (pnt) {
 		pnt += (unsigned long) tpnt->dynamic_info[DT_STRTAB];
 		_dl_if_debug_dprint("\tsearching RUNPATH='%s'\n", pnt);
-		if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt)) != NULL)
+		if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt, NULL)) != NULL)
 			return tpnt1;
 	}
 #endif
@@ -287,7 +295,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
 	/* Look for libraries wherever the shared library loader
 	 * was installed */
 	_dl_if_debug_dprint("\tsearching ldso dir='%s'\n", _dl_ldsopath);
-	tpnt1 = search_for_named_library(libname, secure, _dl_ldsopath, rpnt);
+	tpnt1 = search_for_named_library(libname, secure, _dl_ldsopath, rpnt, NULL);
 	if (tpnt1 != NULL)
 		return tpnt1;
 
@@ -300,7 +308,7 @@ struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
 #ifndef __LDSO_CACHE_SUPPORT__
 					":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
 #endif
-					, rpnt);
+					, rpnt, NULL);
 	if (tpnt1 != NULL)
 		return tpnt1;
 
diff --git a/ldso/ldso/ldso.c b/ldso/ldso/ldso.c
index 3585cb7e3..df16b4fb7 100644
--- a/ldso/ldso/ldso.c
+++ b/ldso/ldso/ldso.c
@@ -268,6 +268,20 @@ static void __attribute__ ((destructor)) __attribute_used__ _dl_fini(void)
 	}
 }
 
+static void _dl_setup_progname(const char *argv0)
+{
+	char image[PATH_MAX];
+	ssize_t s;
+
+	s = _dl_readlink("/proc/self/exe", image, sizeof(image));
+	if (s > 0 && image[0] == '/') {
+		image[s] = 0;
+		_dl_progname = _dl_strdup(image);
+	} else if (argv0) {
+		_dl_progname = argv0;
+	}
+}
+
 void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 			  ElfW(auxv_t) auxvt[AT_EGID + 1], char **envp,
 			  char **argv
@@ -317,9 +331,7 @@ void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 	 * been fixed up by now.  Still no function calls outside of this
 	 * library, since the dynamic resolver is not yet ready.
 	 */
-	if (argv[0]) {
-		_dl_progname = argv[0];
-	}
+	_dl_setup_progname(argv[0]);
 
 	if (_start == (void *) auxvt[AT_ENTRY].a_un.a_val) {
 		_dl_dprintf(_dl_debug_file, "Standalone execution is not supported yet\n");