dyncall: dynload/dynload_unix.c comparison

comparison dynload/dynload_unix.c @ 315:3840e0188520

- allowing lookup of running executable's path by passing NULL to dynload's dlGetLibraryPath()

author	Tassilo Philipp
date	Wed, 06 Nov 2019 14:13:49 +0100
parents	b2e4e23d9953
children	3df50603afa9

comparison

equal deleted inserted replaced

-:b2e4e23d9953
+:3840e0188520
 #include "../autovar/autovar_OS.h"
 #include <string.h>
 #if defined(__GLIBC__)
-/* @@@ version check glibc correctly... dl_iterate_phdr(): glibc ver >= 2.2.4*/
+/* @@@ version check glibc more precisely... dl_iterate_phdr(): glibc ver >= 2.2.4*/
 #if (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 3)
 #  define DL_USE_GLIBC_ITER_PHDR
 #endif
 /* to access dl_iterate_phdr(), and related w/ glibc */
 #  define _GNU_SOURCE
 #else
 #  define RTLD_LIGHTEST RTLD_LAZY
 #endif
+/* helper copying string if buffer big enough, returning length (without \0) */
+static int dl_strlen_strcpy(char* dst, const char* src, int dstSize)
+{
+int l = strlen(src);
+if(l < dstSize) /* l+'\0' <= bufSize */
+strcpy(dst, src);
+return l;
+}
 /* code for dlGetLibraryPath() is platform specific */
 /* if dlinfo() exists use it (except on glibc, where it exists since version
 * 2.3.3, but its implementation is dangerous, as no checks are done whether
-* the handle is valid, thus rendering the returned values useless): check for
+* the handle is valid, thus rendering the returned values useless) check for
 * RTLD_DI_LINKMAP which is a #define for dlinfo() on most supported targets,
 * or specifically check the OS (e.g. dlinfo() is originally from Solaris) */
 #if (defined(RTLD_DI_LINKMAP) || defined(OS_SunOS)) && !defined(DL_USE_GLIBC_ITER_PHDR)
 #include <link.h>
 int dlGetLibraryPath(DLLib* pLib, char* sOut, int bufSize)
 {
 struct link_map* p = NULL;
 int l = -1;
-if(dlinfo(pLib, RTLD_DI_LINKMAP, &p) == 0 && p) {
+if(dlinfo(pLib ? pLib : RTLD_SELF, RTLD_DI_LINKMAP, &p) == 0)
-l = strlen(p->l_name);
+l = dl_strlen_strcpy(sOut, p->l_name, bufSize);
-if(l < bufSize) /* l+'\0' <= bufSize */
-strcpy(sOut, p->l_name);
-}
 return l+1; /* strlen + '\0' */
 }
 /* specific implementation needed on Darwin -----> */
 int dlGetLibraryPath(DLLib* pLib, char* sOut, int bufSize)
 {
 uint32_t i;
 int l = -1;
-/*if(pLib == RTLD_DEFAULT)
+/* request info about own process? lookup first loaded image */
-return NULL; @@@ return exec's path */
+if(pLib == NULL) {
+const char* libPath = _dyld_get_image_name(0); //@@@ consider using _NSGetExecutablePath()
-/* Darwin's code doesn't come with (non-standard) dlinfo(), so use dyld(1) */
+if(libPath)
-/* code. There doesn't seem to be a direct way to query the library path,  */
+l = dl_strlen_strcpy(sOut, libPath, bufSize);
-/* so "double-load" temporarily all already loaded images (just increases  */
+}
-/* ref count) and compare handles until we found ours. Return the name.    */
+else {
-for(i=_dyld_image_count(); i>0;) /* backwards, ours is more likely at end */
+/* Darwin's code doesn't come with (non-standard) dlinfo(), so use dyld(1)
-{
+* code. There doesn't seem to be a direct way to query the library path,
-const char* libPath = _dyld_get_image_name(--i);
+* so "double-load" temporarily all already loaded images (just increases
-void* lib = dlopen(libPath, RTLD_LIGHTEST);
+* ref count) and compare handles until we found ours. Return the name. */
-if(lib) {
+for(i=_dyld_image_count(); i>0;) /* backwards, ours is more likely at end */
-dlclose(lib);
+{
-/* compare handle pointers' high bits (in low 2 bits some flags might */
+const char* libPath = _dyld_get_image_name(--i);
-/* be stored - should be safe b/c address needs alignment, anywas) */
+void* lib = dlopen(libPath, RTLD_LIGHTEST);
-if(((intptr_t)pLib ^ (intptr_t)lib) < 4) {
+if(lib) {
-l = strlen(libPath);
+dlclose(lib);
-if(l < bufSize) /* l+'\0' <= bufSize */
-strcpy(sOut, libPath);
+/* compare handle pointers' high bits (in low 2 bits some flags might */
-break;
+/* be stored - should be safe b/c address needs alignment, anyways) */
+if(((intptr_t)pLib ^ (intptr_t)lib) < 4) {
+l = dl_strlen_strcpy(sOut, libPath, bufSize);
+break;
+}
 }
 }
 }
 return l+1; /* strlen + '\0' */
 static int iter_phdr_cb(struct dl_phdr_info* info, size_t size, void* data)
 {
 int l = -1;
 iter_phdr_data* d = (iter_phdr_data*)data;
-/* unable to relate info->dlpi_addr directly to our dlopen handle, let's */
+void* lib = NULL;
-/* do what we do on macOS above, re-dlopen the already loaded lib (just  */
-/* increases ref count) and compare handles. */
+/* get loaded object's handle if not requesting info about process itself */
-void* lib = dlopen(info->dlpi_name, RTLD_LIGHTEST);
+if(d->pLib != NULL) {
-if(lib) {
+/* unable to relate info->dlpi_addr directly to our dlopen handle, let's
-dlclose(lib);
+* do what we do on macOS above, re-dlopen the already loaded lib (just
-if(lib == (void*)d->pLib) {
+* increases ref count) and compare handles */
-l = strlen(info->dlpi_name);
+lib = dlopen(info->dlpi_name, RTLD_LIGHTEST);
-if(l < d->bufSize) /* l+'\0' <= bufSize */
+if(lib)
-strcpy(d->sOut, info->dlpi_name);
+dlclose(lib);
+}
+/* compare handles and get name if found; if d->pLib == NULL this will
+enter info on first iterated object, which is the process itself */
+if(lib == (void*)d->pLib) {
+l = dl_strlen_strcpy(d->sOut, info->dlpi_name, d->bufSize);
+/* on some platforms (e.g. Linux) dlpi_name is empty for the main process'
+object, but dlpi_addr is given, in that case lookup name via dladdr */
+if(l == 0 && d->pLib == NULL && (void*)info->dlpi_addr != NULL) {
+Dl_info i;
+if(dladdr((void*)info->dlpi_addr, &i) != 0)
+l = dl_strlen_strcpy(d->sOut, i.dli_fname, d->bufSize);
 }
 }
 return l+1; /* strlen + '\0'; is 0 if lib not found, which continues iter */
 }
 int dlGetLibraryPath(DLLib* pLib, char* sOut, int bufSize)
 {
 /* lt_dlgetinfo, which requires iterating over ltdl stuff, but was unable  */
 /* to get that to work (would also introduce a link dependency on libltdl) */
 int dlGetLibraryPath(DLLib* pLib, char* sOut, int bufSize)
 {
+/*@@@ missing handler for pLib == NULL*/
 /* cross fingers that shared object is standard ELF and look for _fini */
 int l = -1;
 void* s = dlsym((void*)pLib, "_fini");
 if(s) {
 Dl_info i;
-if(dladdr(s, &i) != 0) {
+if(dladdr(s, &i) != 0)
-l = strlen(i.dli_fname);
+l = dl_strlen_strcpy(sOut, i.dli_fname, bufSize);
-if(l < bufSize) /* l+'\0' <= bufSize */
-strcpy(sOut, i.dli_fname);
-}
 }
 return l+1; /* strlen + '\0' */
 }
 #endif

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comparison dynload/dynload_unix.c @ 315:3840e0188520