Added support for searching symbols

6 files changed, 60 insertions, 3 deletions

diff --git a/elf/Makefile b/elf/Makefile
index 0cab8eab..30f5059e 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -33,7 +33,7 @@ all: test-prog test-module
 # The testing user-space application
 test-prog: $(TESTPROG)
 
-$(TESTPROG): elftest.o elf_module.o
+$(TESTPROG): elftest.o elf_module.o elf_utils.o
 	$(CC) -o $@ $^
 
 	
diff --git a/elf/elf_module.c b/elf/elf_module.c
index 22900b7a..0a78b7c0 100644
--- a/elf/elf_module.c
+++ b/elf/elf_module.c
@@ -418,3 +418,25 @@ int module_unload(struct elf_module *module) {
 	
 	return 0;
 }
+
+
+Elf32_Sym *module_find_symbol(const char *name, struct elf_module *module) {
+	unsigned long h = elf_hash((const unsigned char*)name);
+	
+	Elf32_Word *bkt = module->hash_table + 2;
+	Elf32_Word *chn = module->hash_table + 2 + module->hash_table[0];
+	
+	Elf32_Word crt_index = bkt[h % module->hash_table[0]];
+	Elf32_Sym *crt_sym;
+	
+	while (crt_index != STN_UNDEF) {
+		crt_sym = (Elf32_Sym*)(module->sym_table + crt_index*module->syment_size);
+		
+		if (strcmp(name, module->str_table + crt_sym->st_name) == 0)
+			return crt_sym;
+		
+		crt_index = chn[crt_index];
+	}
+	
+	return NULL;
+}
diff --git a/elf/elf_module.h b/elf/elf_module.h
index 46bbfd3b..8a8d4830 100644
--- a/elf/elf_module.h
+++ b/elf/elf_module.h
@@ -73,4 +73,6 @@ extern int module_load(struct elf_module *module);
 // Unloads the module from the system and releases all the associated memory
 extern int module_unload(struct elf_module *module);
 
+extern Elf32_Sym *module_find_symbol(const char *name, struct elf_module *module);
+
 #endif /*ELF_MODULE_H_*/
diff --git a/elf/elf_utils.c b/elf/elf_utils.c
new file mode 100644
index 00000000..b96d1ec6
--- /dev/null
+++ b/elf/elf_utils.c
@@ -0,0 +1,16 @@
+#include "elf_utils.h"
+
+unsigned long elf_hash(const unsigned char *name) {
+	unsigned long h = 0;
+	unsigned long g;
+	
+	while (*name) {
+		h = (h << 4) + *name++;
+		if ((g = h & 0xF0000000))
+			h ^= g >> 24;
+		
+		h &= ~g;
+	}
+	
+	return h;
+}
diff --git a/elf/elf_utils.h b/elf/elf_utils.h
index 5e7387f3..604daa58 100644
--- a/elf/elf_utils.h
+++ b/elf/elf_utils.h
@@ -23,4 +23,6 @@ static inline Elf32_Phdr *elf_get_ph(void *elf_image, int index) {
 	return (Elf32_Phdr*)((Elf32_Off)elf_pht + index * elf_hdr->e_phentsize);
 }
 
+extern unsigned long elf_hash(const unsigned char *name);
+
 #endif /*ELF_UTILS_H_*/
diff --git a/elf/elftest.c b/elf/elftest.c
index 6462ad6a..3495ad11 100644
--- a/elf/elftest.c
+++ b/elf/elftest.c
@@ -11,7 +11,7 @@
 
 void print_usage() {
 	fprintf(stderr, "Usage:\n");
-	fprintf(stderr, "\telftest objfile\n");
+	fprintf(stderr, "\telftest objfile [symbol ...]\n");
 }
 
 int main(int argc, char **argv) {
@@ -23,7 +23,7 @@ int main(int argc, char **argv) {
 	argc--;
 	argv++;
 	
-	if (argc != 1) {
+	if (argc < 1) {
 		print_usage();
 		return 1;
 	}
@@ -51,6 +51,21 @@ int main(int argc, char **argv) {
 		goto error;
 	}
 	
+	argc--;
+	argv++;
+	
+	while (argc > 0) {
+		if (module_find_symbol(argv[0], module) != NULL) {
+			printf("Symbol %s found\n", argv[0]);
+		} else {
+			printf("Symbol %s not found\n", argv[0]);
+		}
+		
+		argc--;
+		argv++;
+	}
+	
+	
 	module_unload(module);
 	
 	modules_term();