take care of a few more magic numbers

R=rsc
DELTA=51  (41 added, 0 deleted, 10 changed)
OCL=31815
CL=31818

src/cmd/6l/asm.c

@@ -126,8 +126,10 @@ asmb(void)
 	uchar *op1;
 	vlong vl, va, fo, w, symo;
 	vlong symdatva = 0x99LL<<32;
+	int strtabindex;
 	Elf64PHdr *ph;
 	Elf64SHdr *sh;
+	char eident[EI_NIDENT];
 
 	if(debug['v'])
 		Bprint(&bso, "%5.2f asmb\n", cputime());
@@ -501,6 +503,7 @@ asmb(void)
 
 		w = STRTABSIZE;
 
+		strtabindex = nume64shdr;
 		sh = newElf64SHdr(".shstrtab");
 		sh->type = SHT_STRTAB;
 		sh->off = fo;
@@ -531,15 +534,19 @@ asmb(void)
 		sh->entsize = 24;
 
 		// write out the main header */
-		strnput("\177ELF", 4);		/* e_ident */
-		cput(2);			/* class = 64 bit */
-		cput(1);			/* data = LSB */
-		cput(1);			/* version = CURRENT */
-		strnput("", 9);
-
-		wputl(2);			/* type = EXEC */
+		memset(eident, 0, sizeof eident);
+		eident[EI_MAG0] = '\177';
+		eident[EI_MAG1] = 'E';
+		eident[EI_MAG2] = 'L';
+		eident[EI_MAG3] = 'F';
+		eident[EI_CLASS] = ELFCLASS64;
+		eident[EI_DATA] = ELFDATA2LSB;
+		eident[EI_VERSION] = EV_CURRENT;
+		strnput(eident, EI_NIDENT);
+
+		wputl(ET_EXEC);			/* type = EXEC */
 		wputl(62);			/* machine = AMD64 */
-		lputl(1L);			/* version = CURRENT */
+		lputl(EV_CURRENT);			/* version = CURRENT */
 		vputl(entryvalue());		/* entry vaddr */
 		vputl(64L);			/* offset to first phdr */
 		vputl(64L+56*nume64phdr);		/* offset to first shdr */
@@ -549,7 +556,7 @@ asmb(void)
 		wputl(nume64phdr);			/* # of Phdrs */
 		wputl(64);			/* Shdr size */
 		wputl(nume64shdr);			/* # of Shdrs */
-		wputl(4);			/* Shdr with strings */
+		wputl(strtabindex);			/* Shdr with strings */
 
 		elf64writephdrs();
 		elf64writeshdrs();

src/cmd/ld/elf64.h

@@ -49,9 +49,10 @@ typedef struct Elf64Hdr		Elf64Hdr;
 typedef struct Elf64SHdr	Elf64SHdr;
 typedef struct Elf64PHdr	Elf64PHdr;
 
+#define	EI_NIDENT	16
 struct Elf64Hdr
 {
-	uchar ident[16];	/* ELF identification */
+	uchar ident[EI_NIDENT];	/* ELF identification */
 	Elf64_Half	type;	/* Object file type */
 	Elf64_Half	machine;	/* Machine type */
 	Elf64_Word	version;	/* Object file version */
@@ -67,6 +68,39 @@ struct Elf64Hdr
 	Elf64_Half	shstrndx;	/* Section name string table index */
 };
 
+/* E ident indexes */
+#define	EI_MAG0	0 	/* File identification */
+#define	EI_MAG1	1
+#define	EI_MAG2	2
+#define	EI_MAG3	3
+#define	EI_CLASS	4	/* File class */
+#define	EI_DATA		5	/* Data encoding */
+#define	EI_VERSION	6	/* File version */
+#define	EI_OSABI	7	/* OS/ABI identification */
+#define	EI_ABIVERSION	8	/* ABI version */
+#define	EI_PAD	9	/*Start of padding bytes */
+
+/* E types */
+#define	ET_NONE	0	/* No file type */
+#define	ET_REL	1	/* Relocatable object file */
+#define	ET_EXEC	2	/* Executable file */
+#define	ET_DYN	3	/* Shared object file */
+#define	ET_CORE	4	/* Core file */
+#define	ET_LOOS 0xFE00	/* Environment-specific use */
+#define	ET_HIOS 0xFEFF
+#define	ET_LOPROC 0xFF00	/* Processor-specific use */
+#define	ET_HIPROC 0xFFFF
+
+/* E classes */
+#define	ELFCLASS32	1 	/* 32-bit objects */
+#define	ELFCLASS64	2	/* 64-bit objects */
+
+/* E endians */
+#define	ELFDATA2LSB	1	/* little-endian */
+#define	ELFDATA2MSB	2	/* big-endian */
+
+#define	EV_CURRENT	1	/* current version of format */
+
 struct Elf64PHdr
 {
 	Elf64_Word	type;	/* Type of segment */