Added support for dladdr()
dladdr() is a GNU extension function, which allows the caller to retrieve symbol information for a specified memory address. It is useful for things like generating backtrace information at runtime. Change-Id: I3a1def1a6c9c666d93e1e97b7d260dfa5b9b79a9
This commit is contained in:
Matt Fischer
Garmin Android technology group
parent
ede2e75f49
commit
e2a8b1fd19
@ -32,10 +32,22 @@
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__BEGIN_DECLS
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typedef struct {
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const char *dli_fname; /* Pathname of shared object that
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contains address */
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void *dli_fbase; /* Address at which shared object
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is loaded */
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const char *dli_sname; /* Name of nearest symbol with address
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lower than addr */
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void *dli_saddr; /* Exact address of symbol named
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in dli_sname */
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} Dl_info;
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extern void* dlopen(const char* filename, int flag);
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extern int dlclose(void* handle);
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extern const char* dlerror(void);
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extern void* dlsym(void* handle, const char* symbol);
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extern int dladdr(void* addr, Dl_info *info);
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enum {
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RTLD_NOW = 0,
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@ -14,12 +14,14 @@
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* limitations under the License.
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*/
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#include <dlfcn.h>
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/* These are stubs for functions that are actually defined
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* in the dynamic linker (dlfcn.c), and hijacked at runtime.
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*/
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void *dlopen(const char *filename, int flag) { return 0; }
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char *dlerror(void) { return 0; }
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const char *dlerror(void) { return 0; }
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void *dlsym(void *handle, const char *symbol) { return 0; }
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int dladdr(void *addr, Dl_info *info) { return 0; }
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int dlclose(void *handle) { return 0; }
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#ifdef __arm__
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@ -117,6 +117,37 @@ err:
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return 0;
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}
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int dladdr(void *addr, Dl_info *info)
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{
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int ret = 0;
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pthread_mutex_lock(&dl_lock);
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/* Determine if this address can be found in any library currently mapped */
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soinfo *si = find_containing_library(addr);
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if(si) {
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memset(info, 0, sizeof(Dl_info));
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info->dli_fname = si->name;
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info->dli_fbase = (void*)si->base;
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/* Determine if any symbol in the library contains the specified address */
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Elf32_Sym *sym = find_containing_symbol(addr, si);
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if(sym != NULL) {
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info->dli_sname = si->strtab + sym->st_name;
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info->dli_saddr = (void*)(si->base + sym->st_value);
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}
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ret = 1;
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}
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pthread_mutex_unlock(&dl_lock);
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return ret;
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}
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int dlclose(void *handle)
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{
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pthread_mutex_lock(&dl_lock);
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@ -126,22 +157,22 @@ int dlclose(void *handle)
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}
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#if defined(ANDROID_ARM_LINKER)
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// 0000000 00011111 111112 22222222 233333333334444444444
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// 0123456 78901234 567890 12345678 901234567890123456789
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// 0000000 00011111 111112 22222222 2333333 333344444444445555555
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// 0123456 78901234 567890 12345678 9012345 678901234567890123456
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#define ANDROID_LIBDL_STRTAB \
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"dlopen\0dlclose\0dlsym\0dlerror\0dl_unwind_find_exidx\0"
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"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0dl_unwind_find_exidx\0"
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#elif defined(ANDROID_X86_LINKER)
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// 0000000 00011111 111112 22222222 2333333333344444
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// 0123456 78901234 567890 12345678 9012345678901234
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// 0000000 00011111 111112 22222222 2333333 3333444444444455
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// 0123456 78901234 567890 12345678 9012345 6789012345678901
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#define ANDROID_LIBDL_STRTAB \
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"dlopen\0dlclose\0dlsym\0dlerror\0dl_iterate_phdr\0"
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"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0dl_iterate_phdr\0"
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#elif defined(ANDROID_SH_LINKER)
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// 0000000 00011111 111112 22222222 2333333333344444
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// 0123456 78901234 567890 12345678 9012345678901234
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// 0000000 00011111 111112 22222222 2333333 3333444444444455
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// 0123456 78901234 567890 12345678 9012345 6789012345678901
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#define ANDROID_LIBDL_STRTAB \
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"dlopen\0dlclose\0dlsym\0dlerror\0dl_iterate_phdr\0"
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"dlopen\0dlclose\0dlsym\0dlerror\0dladdr\0dl_iterate_phdr\0"
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#else /* !defined(ANDROID_ARM_LINKER) && !defined(ANDROID_X86_LINKER) */
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#error Unsupported architecture. Only ARM and x86 are presently supported.
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@ -175,20 +206,25 @@ static Elf32_Sym libdl_symtab[] = {
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st_info: STB_GLOBAL << 4,
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st_shndx: 1,
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},
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#ifdef ANDROID_ARM_LINKER
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{ st_name: 29,
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st_value: (Elf32_Addr) &dladdr,
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st_info: STB_GLOBAL << 4,
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st_shndx: 1,
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},
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#ifdef ANDROID_ARM_LINKER
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{ st_name: 36,
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st_value: (Elf32_Addr) &dl_unwind_find_exidx,
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st_info: STB_GLOBAL << 4,
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st_shndx: 1,
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},
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#elif defined(ANDROID_X86_LINKER)
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{ st_name: 29,
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{ st_name: 36,
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st_value: (Elf32_Addr) &dl_iterate_phdr,
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st_info: STB_GLOBAL << 4,
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st_shndx: 1,
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},
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#elif defined(ANDROID_SH_LINKER)
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{ st_name: 29,
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{ st_name: 36,
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st_value: (Elf32_Addr) &dl_iterate_phdr,
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st_info: STB_GLOBAL << 4,
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st_shndx: 1,
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@ -216,7 +252,7 @@ static Elf32_Sym libdl_symtab[] = {
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* stubbing them out in libdl.
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*/
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static unsigned libdl_buckets[1] = { 1 };
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static unsigned libdl_chains[6] = { 0, 2, 3, 4, 5, 0 };
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static unsigned libdl_chains[7] = { 0, 2, 3, 4, 5, 6, 0 };
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soinfo libdl_info = {
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name: "libdl.so",
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@ -226,7 +262,7 @@ soinfo libdl_info = {
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symtab: libdl_symtab,
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nbucket: 1,
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nchain: 6,
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nchain: 7,
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bucket: libdl_buckets,
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chain: libdl_chains,
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};
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@ -538,6 +538,40 @@ Elf32_Sym *lookup(const char *name, soinfo **found)
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return 0;
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}
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soinfo *find_containing_library(void *addr)
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{
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soinfo *si;
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for(si = solist; si != NULL; si = si->next)
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{
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if((unsigned)addr >= si->base && (unsigned)addr - si->base < si->size) {
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return si;
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}
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}
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return NULL;
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}
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Elf32_Sym *find_containing_symbol(void *addr, soinfo *si)
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{
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unsigned int i;
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unsigned soaddr = (unsigned)addr - si->base;
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/* Search the library's symbol table for any defined symbol which
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* contains this address */
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for(i=0; i<si->nchain; i++) {
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Elf32_Sym *sym = &si->symtab[i];
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if(sym->st_shndx != SHN_UNDEF &&
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soaddr >= sym->st_value &&
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soaddr < sym->st_value + sym->st_size) {
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return sym;
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}
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}
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return NULL;
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}
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#if 0
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static void dump(soinfo *si)
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{
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@ -225,6 +225,8 @@ soinfo *find_library(const char *name);
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unsigned unload_library(soinfo *si);
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Elf32_Sym *lookup_in_library(soinfo *si, const char *name);
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Elf32_Sym *lookup(const char *name, soinfo **found);
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soinfo *find_containing_library(void *addr);
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Elf32_Sym *find_containing_symbol(void *addr, soinfo *si);
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const char *linker_get_error(void);
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#ifdef ANDROID_ARM_LINKER
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