[RFC] [PATCH] ldso: limited support for $ORIGIN in rpath

Derived from:
http://lists.busybox.net/pipermail/uclibc/2011-March/045003.html

However, the above patch introduced '_dl_strchr' in ldso/ldso/dl-elf.c,
and caused the following undefined referencing compiling error:

  | .../libdl.a(libdl.os): In function `search_for_named_library':
  | .../dl-elf.c:156: undefined reference to `_dl_strchr'
  | collect2: error: ld returned 1 exit status

This problem would be reproduced through compiling gdb in static mode
using uclibc.

So, add the definition of '_dl_strchr' to fix it. The '_dl_strstr' is
added as well.

Signed-off-by: Timo Teräs <timo.teras at iki.fi>
Signed-off-by: Junling Zheng <[email protected]>
---
 ldso/include/dl-string.h |  2 ++
 ldso/ldso/dl-elf.c       | 79 +++++++++++++++++++++++++-----------------------
 ldso/ldso/ldso.c         | 18 +++++++++--
 3 files changed, 59 insertions(+), 40 deletions(-)

diff --git a/ldso/include/dl-string.h b/ldso/include/dl-string.h
index aacad10..14ae617 100644
--- a/ldso/include/dl-string.h
+++ b/ldso/include/dl-string.h
@@ -204,7 +204,9 @@ static __always_inline char * _dl_get_last_path_component(char *path)
 # define _dl_strcat strcat
 # define _dl_strcpy strcpy
 # define _dl_strcmp strcmp
+# define _dl_strchr strchr
 # define _dl_strrchr strrchr
+# define _dl_strstr strstr
 # define _dl_memcpy memcpy
 # define _dl_memcmp memcmp
 # define _dl_memset memset
diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c
index 5631905..6ab7afe 100644
--- a/ldso/ldso/dl-elf.c
+++ b/ldso/ldso/dl-elf.c
@@ -133,56 +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, unsigned rflags, 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;
+	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 (rflags && 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, ".");
 		}
-		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);
+		_dl_strcat(mylibname, "/");
+		_dl_strcat(mylibname, name);
 #ifdef __LDSO_SAFE_RUNPATH__
-			if (*mylibname == '/')
+		if (*mylibname == '/')
 #endif
-				if ((tpnt = _dl_load_elf_shared_library(rflags, rpnt, mylibname)) != NULL)
-					return tpnt;
-			path_n = path+1;
-		}
-		path++;
-	} while (!done);
+		if ((tpnt = _dl_load_elf_shared_library(rflags, rpnt, mylibname)) != NULL)
+			return tpnt;
+	}
 	return NULL;
 }
 
@@ -234,7 +238,8 @@ struct elf_resolve *_dl_load_shared_library(unsigned rflags, struct dyn_elf **rp
 	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, rflags, pnt, rpnt)) != NULL)
+		if ((tpnt1 = search_for_named_library(libname, rflags, pnt, rpnt,
+						      tpnt->libname)) != NULL)
 			return tpnt1;
 	}
 #endif
@@ -243,7 +248,7 @@ struct elf_resolve *_dl_load_shared_library(unsigned rflags, struct dyn_elf **rp
 	/* 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, rflags, _dl_library_path, rpnt)) != NULL)
+		if ((tpnt1 = search_for_named_library(libname, rflags, _dl_library_path, rpnt, NULL)) != NULL)
 		{
 			return tpnt1;
 		}
@@ -257,7 +262,7 @@ struct elf_resolve *_dl_load_shared_library(unsigned rflags, struct dyn_elf **rp
 	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, rflags, pnt, rpnt)) != NULL)
+		if ((tpnt1 = search_for_named_library(libname, rflags, pnt, rpnt, NULL)) != NULL)
 			return tpnt1;
 	}
 #endif
@@ -291,7 +296,7 @@ struct elf_resolve *_dl_load_shared_library(unsigned rflags, struct dyn_elf **rp
 	/* 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, rflags, _dl_ldsopath, rpnt);
+	tpnt1 = search_for_named_library(libname, rflags, _dl_ldsopath, rpnt, NULL);
 	if (tpnt1 != NULL)
 		return tpnt1;
 #endif
@@ -304,7 +309,7 @@ struct elf_resolve *_dl_load_shared_library(unsigned rflags, struct dyn_elf **rp
 #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 5619629..73bcc41 100644
--- a/ldso/ldso/ldso.c
+++ b/ldso/ldso/ldso.c
@@ -402,6 +402,20 @@ static ptrdiff_t _dl_build_local_scope (struct elf_resolve **list,
 				p += _dl_build_local_scope (p, q->tpnt);
 	return p - list;
 }
+ 
+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
@@ -454,9 +468,7 @@ 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]);
 
 #ifdef __DSBT__
 	_dl_ldso_dsbt = (void *)tpnt->dynamic_info[DT_DSBT_BASE_IDX];
-- 
1.8.3.4

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