Teach ldd to act just the glibc provided one (relying on the

shared lib loader to do the work) when it is possible to do
so, and only go poking about through the ELF headers when that
fails so we can still use 'ldd' on cross compiled stuff.
 -Erik

2 files changed, 93 insertions, 7 deletions

diff --git a/ldso/util/Makefile b/ldso/util/Makefile
index 0f36bd31e..7d49ee523 100644
--- a/ldso/util/Makefile
+++ b/ldso/util/Makefile
@@ -33,6 +33,10 @@ TARGETS += ldconfig
 endif
 all: $(TARGETS)
 
+ifeq ($(strip $(LDSO_LDD_SUPPORT)),y)
+XXFLAGS=-D__LDSO_LDD_SUPPORT
+endif
+
 elf_header:
 	ln -fs $(TOPDIR)include/elf.h
 
@@ -58,7 +62,7 @@ ldconfig: ldconfig.o readsoname.o
 	strip -x -R .note -R .comment $@
 
 ldd: ldd.c
-	$(HOSTCC) $(HOSTCFLAGS) -DUCLIBC_TARGET_PREFIX=\"$(TARGET_PREFIX)\" \
+	$(HOSTCC) $(HOSTCFLAGS) $(XXFLAGS) -DUCLIBC_TARGET_PREFIX=\"$(TARGET_PREFIX)\" \
 		-DUCLIBC_DEVEL_PREFIX=\"$(DEVEL_PREFIX)\" \
 		-DUCLIBC_BUILD_DIR=\"$(shell cd $(TOPDIR) && pwd)\" \
 		-DUCLIBC_LDSO=\"$(UCLIBC_LDSO)\" -I . \
@@ -66,7 +70,7 @@ ldd: ldd.c
 	strip -x -R .note -R .comment $@
 
 ldd.target: ldd.c
-	$(TARGET_CC) $(CFLAGS) -Wl,-s -DUCLIBC_TARGET_PREFIX=\"$(TARGET_PREFIX)\" \
+	$(TARGET_CC) $(CFLAGS) $(XXFLAGS) -Wl,-s -DUCLIBC_TARGET_PREFIX=\"$(TARGET_PREFIX)\" \
 		-DUCLIBC_DEVEL_PREFIX=\"$(DEVEL_PREFIX)\" \
 		-DUCLIBC_BUILD_DIR=\"$(shell cd $(TOPDIR) && pwd)\" \
 		-DUCLIBC_LDSO=\"$(UCLIBC_LDSO)\" \
diff --git a/ldso/util/ldd.c b/ldso/util/ldd.c
index 7fdeaf5b0..664f55a4f 100644
--- a/ldso/util/ldd.c
+++ b/ldso/util/ldd.c
@@ -49,6 +49,59 @@
 #include <dmalloc.h>
 #endif
 
+#if defined(__arm__)
+#define MATCH_MACHINE(x) (x == EM_ARM)
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#if defined(__s390__)
+#define MATCH_MACHINE(x) (x == EM_S390)
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#if defined(__i386__)
+#ifndef EM_486
+#define MATCH_MACHINE(x) (x == EM_386)
+#else
+#define MATCH_MACHINE(x) (x == EM_386 || x == EM_486)
+#endif
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#if defined(__mc68000__) 
+#define MATCH_MACHINE(x) (x == EM_68K)
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#if defined(__mips__)
+#define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE)
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#if defined(__powerpc__)
+#define MATCH_MACHINE(x) (x == EM_PPC)
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#if defined(__sh__)
+#define MATCH_MACHINE(x) (x == EM_SH)
+#endif
+
+#if defined (__v850e__)
+#define MATCH_MACHINE(x) ((x) == EM_V850 || (x) == EM_CYGNUS_V850)
+#define ELFCLASSM	ELFCLASS32
+#endif
+
+#ifndef MATCH_MACHINE
+#warning "You really should add a MATCH_MACHINE() macro for your architecture"
+#endif
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define ELFDATAM	ELFDATA2LSB
+#elif __BYTE_ORDER == __BIG_ENDIAN
+#define ELFDATAM	ELFDATA2MSB
+#endif
+
 struct library {
 	char *name;
 	int resolved;
@@ -132,6 +185,7 @@ int check_elf_header(Elf32_Ehdr *const ehdr)
 	}
 #elif __BYTE_ORDER == __BIG_ENDIAN
 	if (ehdr->e_ident[5] == ELFDATA2LSB) {
+		/* Ick -- we will have to byte-swap everything */
 		byteswap = 1;
 	}
 #else
@@ -347,13 +401,14 @@ static void find_needed_libraries(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, char *st
 	}
 }
     
-static void find_elf_interpreter(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, char *strtab, int is_setuid)
+static struct library * 
+find_elf_interpreter(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, char *strtab, int is_setuid)
 {
 	static int been_there_done_that=0;
 	Elf32_Phdr *phdr;
 
 	if (been_there_done_that==1)
-		return;
+		return NULL;
 	been_there_done_that=1;
 	phdr = elf_find_phdr_type(PT_INTERP, ehdr);
 	if (phdr) {
@@ -383,13 +438,13 @@ static void find_elf_interpreter(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, char *str
 				newlib = cur;
 				free(newlib->name);
 				free(newlib->path);
-				return;
+				return NULL;
 			}
 		}
 		if (newlib == NULL)
 			newlib = malloc(sizeof(struct library));
 		if (!newlib)
-			return;
+			return NULL;
 		newlib->name = malloc(strlen(s)+1);
 		strcpy(newlib->name, s);
 		newlib->path = newlib->name;
@@ -405,7 +460,9 @@ static void find_elf_interpreter(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, char *str
 			cur->next = newlib;
 		}
 #endif
+		return newlib;
 	}
+	return NULL;
 }
 
 /* map the .so, and locate interesting pieces */
@@ -418,6 +475,7 @@ int find_dependancies(char* filename)
 	Elf32_Ehdr *ehdr = NULL;
 	Elf32_Shdr *dynsec = NULL;
 	Elf32_Dyn *dynamic = NULL;
+	struct library *interp;
 
 	if (filename == not_found)
 		return 0;
@@ -464,7 +522,31 @@ foo:
 	}
 
 	dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr);
-	find_elf_interpreter(ehdr, dynamic, dynstr, is_suid);
+	interp = find_elf_interpreter(ehdr, dynamic, dynstr, is_suid);
+			
+#ifdef __LDSO_LDD_SUPPORT
+	if (interp && ehdr->e_ident[EI_CLASS] == ELFCLASSM && ehdr->e_ident[EI_DATA] == ELFDATAM
+		&& ehdr->e_ident[EI_VERSION] == EV_CURRENT && MATCH_MACHINE(ehdr->e_machine)) 
+	{
+		struct stat statbuf;
+		if (stat(interp->path, &statbuf) == 0 && S_ISREG(statbuf.st_mode)) {
+			static const char * const environment[] = {
+				"PATH=/usr/bin:/bin:/usr/sbin:/sbin",
+				"SHELL=/bin/sh",
+				"LD_TRACE_LOADED_OBJECTS=1",
+				NULL
+			};
+			/* Cool, it looks like we should be able to actually 
+			 * run this puppy.  Do so now... */
+			execle(filename, filename, NULL, environment);
+
+			/* If the exec failed, we fall through to trying to find
+			 * all the needed libraries ourselves by rummaging about
+			 * in the ELF headers... */
+		}
+	}
+#endif
+
 	if (dynsec) {
 		dynamic = (Elf32_Dyn*)(byteswap32_to_host(dynsec->sh_offset) + (intptr_t)ehdr);
 		dynstr = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0);