libmach: many pe handling fixes

- implement windows pread;
- set correct Fhdr.type;
- add ImageBase to all pe "virtual" addresses;
- correct settext parameter order;
- use pclntab/epclntab to find line numbers.

Fixes #4841.
Fixes #4926.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7405050

src/libmach/executable.c

@@ -1349,12 +1349,12 @@ static int
 pedotout(int fd, Fhdr *fp, ExecHdr *hp)
 {
 	uint32 start, magic;
-	uint32 symtab, esymtab;
+	uint32 symtab, esymtab, pclntab, epclntab;
 	IMAGE_FILE_HEADER fh;
 	IMAGE_SECTION_HEADER sh;
 	IMAGE_OPTIONAL_HEADER oh;
 	uint8 sym[18];
-	uint32 *valp;
+	uint32 *valp, ib;
 	int i;
 
 	USED(hp);
@@ -1389,6 +1389,19 @@ pedotout(int fd, Fhdr *fp, ExecHdr *hp)
 		return 0;
 	}
 
+	switch(oh.Magic) {
+	case 0x10b:	// PE32
+		fp->type = FI386;
+		break;
+	case 0x20b:	// PE32+
+		fp->type = FAMD64;
+		break;
+	default:
+		werrstr("invalid PE Optional magic number");
+		return 0;
+	}
+
+	ib=leswal(oh.ImageBase);
 	seek(fd, start+sizeof(magic)+sizeof(fh)+leswab(fh.SizeOfOptionalHeader), 0);
 	fp->txtaddr = 0;
 	fp->dataddr = 0;
@@ -1398,17 +1411,17 @@ pedotout(int fd, Fhdr *fp, ExecHdr *hp)
 			return 0;
 		}
 		if (match8(sh.Name, ".text"))
-			settext(fp, leswal(sh.VirtualAddress), leswal(oh.AddressOfEntryPoint), leswal(sh.VirtualSize), leswal(sh.PointerToRawData));
+			settext(fp, ib+leswal(oh.AddressOfEntryPoint), ib+leswal(sh.VirtualAddress), leswal(sh.VirtualSize), leswal(sh.PointerToRawData));
 		if (match8(sh.Name, ".data"))
-			setdata(fp, leswal(sh.VirtualAddress), leswal(sh.SizeOfRawData), leswal(sh.PointerToRawData), leswal(sh.VirtualSize)-leswal(sh.SizeOfRawData));
+			setdata(fp, ib+leswal(sh.VirtualAddress), leswal(sh.SizeOfRawData), leswal(sh.PointerToRawData), leswal(sh.VirtualSize)-leswal(sh.SizeOfRawData));
 	}
 	if (fp->txtaddr==0 || fp->dataddr==0) {
 		werrstr("no .text or .data");
 		return 0;
 	}
 
 	seek(fd, leswal(fh.PointerToSymbolTable), 0);
-	symtab = esymtab = 0;
+	symtab = esymtab = pclntab = epclntab = 0;
 	for (i=0; i<leswal(fh.NumberOfSymbols); i++) {
 		if (readn(fd, sym, sizeof(sym)) != sizeof(sym)) {
 			werrstr("crippled COFF symbol %d", i);
@@ -1419,12 +1432,16 @@ pedotout(int fd, Fhdr *fp, ExecHdr *hp)
 			symtab = leswal(*valp);
 		if (match8(sym, "esymtab"))
 			esymtab = leswal(*valp);
+		if (match8(sym, "pclntab"))
+			pclntab = leswal(*valp);
+		if (match8(sym, "epclntab"))
+			epclntab = leswal(*valp);
 	}
-	if (symtab==0 || esymtab==0) {
-		werrstr("no symtab or esymtab in COFF symbol table");
+	if (symtab==0 || esymtab==0 || pclntab==0 || epclntab==0) {
+		werrstr("no symtab or esymtab or pclntab or epclntab in COFF symbol table");
 		return 0;
 	}
-	setsym(fp, symtab, esymtab-symtab, 0, 0, 0, 0);
+	setsym(fp, symtab, esymtab-symtab, 0, 0, pclntab, epclntab-pclntab);
 
 	return 1;
 }

src/libmach/windows.c

@@ -48,8 +48,12 @@ procthreadpids(int pid, int *p, int np)
 int 
 pread(int fd, void *buf, int count, int offset)
 {
-	sysfatal("pread unimplemented in Windows");
-	return -1;
+	int oldoffset, n;
+
+	oldoffset = seek(fd, offset, 0);
+	n = read(fd, buf, count);
+	seek(fd, oldoffset, 0);
+	return n;
 }
 
 int