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runtime: fix endianness assumption when decoding ftab

The ftab ends with a half functab record consisting only of
the 'entry' field followed by a uint32 giving the offset of
the next table.  Previously, symtabinit assumed it could read
this uint32 as a uintptr.  Since this is unsafe on big endian,
explicitly read the offset as a uint32.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/157660043
This commit is contained in:
Austin Clements 2014-10-27 17:12:48 -04:00
parent 77595e462b
commit 3e62d2184a

View File

@ -84,10 +84,13 @@ func symtabinit() {
}
}
// file table follows ftab.
// The ftab ends with a half functab consisting only of
// 'entry', followed by a uint32 giving the pcln-relative
// offset of the file table.
sp = (*sliceStruct)(unsafe.Pointer(&filetab))
p = unsafe.Pointer(add(unsafe.Pointer(pcln), ftab[nftab].funcoff))
sp.array = unsafe.Pointer(add(unsafe.Pointer(pcln), ftab[nftab].funcoff))
end := unsafe.Pointer(&ftab[nftab].funcoff) // just beyond ftab
fileoffset := *(*uint32)(end)
sp.array = unsafe.Pointer(&pclntable[fileoffset])
// length is in first element of array.
// set len to 1 so we can get first element.
sp.len = 1
@ -224,7 +227,7 @@ func funcline(f *_func, targetpc uintptr, file *string) int32 {
func funcspdelta(f *_func, targetpc uintptr) int32 {
x := pcvalue(f, f.pcsp, targetpc, true)
if x&(ptrSize-1) != 0 {
print("invalid spdelta ", f.pcsp, " ", x, "\n")
print("invalid spdelta ", hex(f.entry), " ", hex(targetpc), " ", hex(f.pcsp), " ", x, "\n")
}
return x
}