tcc -ar: pad archive member position to even

Since commit 45cff8f0 tcc eventually generates object files
of non-even size.

tccelf.c:
- check ARFMAG for better invalid archive detection
- file_offset needs to be aligned, not the size (just a nitpick)
lib/Makefile:
- remake everything when tcc did change

lib/Makefile

@@ -8,6 +8,7 @@ VPATH = $(TOPSRC)/lib $(TOPSRC)/win32/lib
 T = $(or $(CROSS_TARGET),$(NATIVE_TARGET),unknown)
 X = $(if $(CROSS_TARGET),$(CROSS_TARGET)-)
 
+TCC = $(TOP)/$(X)tcc$(EXESUF)
 XTCC ?= $(TOP)/$(X)tcc$(EXESUF)
 XCC = $(XTCC)
 XAR = $(XTCC) -ar
@@ -44,6 +45,9 @@ $(X)BT_O += runmain.o tcov.o
 
 DSO_O = dsohandle.o
 
+# not in libtcc1.a
+EXTRA_O = runmain.o bt-exe.o bt-dll.o bt-log.o bcheck.o
+
 I386_O = libtcc1.o alloca.o alloca-bt.o stdatomic.o atomic.o builtin.o $(BT_O)
 X86_64_O = libtcc1.o alloca.o alloca-bt.o stdatomic.o atomic.o builtin.o $(BT_O)
 ARM_O = libtcc1.o armeabi.o alloca.o armflush.o stdatomic.o atomic.o builtin.o $(BT_O)
@@ -67,23 +71,23 @@ OBJ-arm-eabihf = $(ARM_O) $(DSO_O)
 OBJ-arm-wince = $(ARM_O) $(WIN_O)
 OBJ-riscv64 = $(RISCV64_O) $(BCHECK_O) $(DSO_O)
 
-OBJ-extra = $(filter $(B_O) runmain.o,$(OBJ-$T))
+OBJ-extra = $(filter $(EXTRA_O),$(OBJ-$T))
 OBJ-libtcc1 = $(addprefix $(X),$(filter-out $(OBJ-extra),$(OBJ-$T)))
 
 ALL = $(addprefix $(TOP)/,$(X)libtcc1.a $(OBJ-extra))
 
 all: $(ALL)
 
-$(TOP)/$(X)libtcc1.a : $(OBJ-libtcc1)
+$(TOP)/$(X)libtcc1.a : $(OBJ-libtcc1) $(TCC)
-	$S$(XAR) rcs $@ $^
+	$S$(XAR) rcs $@ $(OBJ-libtcc1)
 
-$(X)%.o : %.c
+$(X)%.o : %.c $(TCC)
 	$S$(XCC) -c $< -o $@ $(XFLAGS)
 
-$(X)%.o : %.S
+$(X)%.o : %.S $(TCC)
 	$S$(XCC) -c $< -o $@ $(XFLAGS)
 
-$(TOP)/%.o : %.c
+$(TOP)/%.o : %.c $(TCC)
 	$S$(XCC) -c $< -o $@ $(XFLAGS)
 
 $(TOP)/bcheck.o : XFLAGS += $(BFLAGS) $(if $(CONFIG_musl),-DTCC_MUSL)
@@ -92,5 +96,8 @@ $(TOP)/bt-exe.o : $(TOP)/tccrun.c
 $(X)crt1w.o : crt1.c
 $(X)wincrt1w.o : wincrt1.c
 
+# don't try to make it
+$(TCC) : ;
+
 clean :
-	rm -f *.a *.o $(ALL)
+	rm -f *.o $(addprefix $(TOP)/,*libtcc1.a $(EXTRA_O))

tccelf.c

@@ -3374,6 +3374,8 @@ static int read_ar_header(int fd, int offset, ArchiveHeader *hdr)
     len = full_read(fd, hdr, sizeof(ArchiveHeader));
     if (len != sizeof(ArchiveHeader))
         return len ? -1 : 0;
+    if (memcmp(hdr->ar_fmag, ARFMAG, sizeof hdr->ar_fmag))
+        return -1;
     p = hdr->ar_name;
     for (e = p + sizeof hdr->ar_name; e > p && e[-1] == ' ';)
         --e;
@@ -3451,8 +3453,6 @@ ST_FUNC int tcc_load_archive(TCCState *s1, int fd, int alacarte)
             return tcc_error_noabort("invalid archive");
         file_offset += len;
         size = strtol(hdr.ar_size, NULL, 0);
-        /* align to even */
-        size = (size + 1) & ~1;
         if (alacarte) {
             /* coff symbol table : we handle it */
             if (!strcmp(hdr.ar_name, "/"))
@@ -3465,7 +3465,8 @@ ST_FUNC int tcc_load_archive(TCCState *s1, int fd, int alacarte)
             if (tcc_load_object_file(s1, fd, file_offset) < 0)
                 return -1;
         }
-        file_offset += size;
+        /* align to even */
+        file_offset = (file_offset + size + 1) & ~1;
     }
 }
 

tcctools.c

@@ -87,7 +87,7 @@ ST_FUNC int tcc_tool_ar(TCCState *s1, int argc, char **argv)
     ElfW(Shdr) *shdr;
     ElfW(Sym) *sym;
     int i, fsize, i_lib, i_obj;
-    char *buf, *shstr, *symtab = NULL, *strtab = NULL;
+    char *buf, *shstr, *symtab, *strtab;
     int symtabsize = 0;//, strtabsize = 0;
     char *anames = NULL;
     int *afpos = NULL;
@@ -174,6 +174,8 @@ no_ar:
 		    /* ignore date/uid/gid/mode */
 		}
 	    }
+            if (fsize & 1)
+                fgetc(fh);
             tcc_free(buf);
 	}
 	ret = 0;
@@ -232,6 +234,7 @@ finish:
 
         shdr = (ElfW(Shdr) *) (buf + ehdr->e_shoff + ehdr->e_shstrndx * ehdr->e_shentsize);
         shstr = (char *)(buf + shdr->sh_offset);
+        symtab = strtab = NULL;
         for (i = 0; i < ehdr->e_shnum; i++)
         {
             shdr = (ElfW(Shdr) *) (buf + ehdr->e_shoff + i * ehdr->e_shentsize);
@@ -252,7 +255,7 @@ finish:
             }
         }
 
-        if (symtab && symtabsize)
+        if (symtab && strtab)
         {
             int nsym = symtabsize / sizeof(ElfW(Sym));
             //printf("symtab: info size shndx name\n");
@@ -298,6 +301,8 @@ finish:
         tcc_free(buf);
         i_obj++;
         fpos += (fsize + sizeof(arhdro));
+        if (fpos & 1)
+            fputc(0, fo), ++fpos;
     }
     hofs = 8 + sizeof(arhdr) + strpos + (funccnt+1) * sizeof(int);
     fpos = 0;