libmach

1 files changed, 217 insertions, 0 deletions

diff --git a/src/libmach/dwarfget.c b/src/libmach/dwarfget.c
new file mode 100644
index 00000000..da8558c4
--- /dev/null
+++ b/src/libmach/dwarfget.c
@@ -0,0 +1,217 @@
+/*
+ * Dwarf data format parsing routines.
+ */
+
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include "elf.h"
+#include "dwarf.h"
+
+ulong
+dwarfget1(DwarfBuf *b)
+{
+	if(b->p==nil || b->p+1 > b->ep){
+		b->p = nil;
+		return 0;
+	}
+	return *b->p++;
+}
+
+int
+dwarfgetn(DwarfBuf *b, uchar *a, int n)
+{
+	if(b->p==nil || b->p+n > b->ep){
+		b->p = nil;
+		memset(a, 0, n);
+		return -1;
+	}
+	memmove(a, b->p, n);
+	b->p += n;
+	return 0;
+}
+
+uchar*
+dwarfgetnref(DwarfBuf *b, ulong n)
+{
+	uchar *p;
+
+	if(b->p==nil || b->p+n > b->ep){
+		b->p = nil;
+		return nil;
+	}
+	p = b->p;
+	b->p += n;
+	return p;
+}
+
+char*
+dwarfgetstring(DwarfBuf *b)
+{
+	char *s;
+
+	if(b->p == nil)
+		return nil;
+	s = (char*)b->p;
+	while(b->p < b->ep && *b->p)
+		b->p++;
+	if(b->p >= b->ep){
+		b->p = nil;
+		return nil;
+	}
+	b->p++;
+	return s;
+}
+
+void
+dwarfskip(DwarfBuf *b, int n)
+{
+	if(b->p==nil || b->p+n > b->ep)
+		b->p = nil;
+	else
+		b->p += n;
+}
+
+ulong
+dwarfget2(DwarfBuf *b)
+{
+	ulong v;
+
+	if(b->p==nil || b->p+2 > b->ep){
+		b->p = nil;
+		return 0;
+	}
+	v = b->d->elf->hdr.e2(b->p);
+	b->p += 2;
+	return v;
+}
+
+ulong
+dwarfget4(DwarfBuf *b)
+{
+	ulong v;
+
+	if(b->p==nil || b->p+4 > b->ep){
+		b->p = nil;
+		return 0;
+	}
+	v = b->d->elf->hdr.e4(b->p);
+	b->p += 4;
+	return v;
+}
+
+uvlong
+dwarfget8(DwarfBuf *b)
+{
+	uvlong v;
+
+	if(b->p==nil || b->p+8 > b->ep){
+		b->p = nil;
+		return 0;
+	}
+	v = b->d->elf->hdr.e8(b->p);
+	b->p += 8;
+	return v;
+}
+
+ulong
+dwarfgetaddr(DwarfBuf *b)
+{
+	static int nbad;
+
+	if(b->addrsize == 0)
+		b->addrsize = b->d->addrsize;
+
+	switch(b->addrsize){
+	case 1:
+		return dwarfget1(b);
+	case 2:
+		return dwarfget2(b);
+	case 4:
+		return dwarfget4(b);
+	case 8:
+		return dwarfget8(b);
+	default:
+		if(++nbad == 1)
+			fprint(2, "dwarf: unexpected address size %lud in dwarfgetaddr\n", b->addrsize);
+		b->p = nil;
+		return 0;
+	}
+}
+
+int n1, n2, n3, n4, n5;
+
+/* An inline function picks off the calls to dwarfget128 for 1-byte encodings,
+ * more than by far the common case (99.999% on most binaries!). */
+ulong
+dwarfget128(DwarfBuf *b)
+{
+	static int nbad;
+	ulong c, d;
+
+	if(b->p == nil)
+		return 0;
+	c = *b->p++;
+	if(!(c&0x80))
+{n1++;
+		return c;
+}
+	d = *b->p++;
+	c |= (d&0x7F)<<7;
+	if(!(d&0x80))
+{n2++;
+		return c;
+}
+	d = *b->p++;
+	c |= (d&0x7F)<<14;
+	if(!(d&0x80))
+{n3++;
+		return c;
+}
+	d = *b->p++;
+	c |= (d&0x7F)<<21;
+	if(!(d&0x80))
+{n4++;
+		return c;
+}
+	d = *b->p++;
+	c |= (d&0x7F)<<28;
+	if(!(d&0x80))
+{n5++;
+		return c;
+}
+	while(b->p<b->ep && *b->p&0x80)
+		b->p++;
+	if(++nbad == 1)
+		fprint(2, "dwarf: overflow during parsing of uleb128 integer\n");
+	return c;
+}
+
+long
+dwarfget128s(DwarfBuf *b)
+{
+	int nb, c;
+	ulong v;
+	static int nbad;
+
+	v = 0;
+	nb = 0;
+	if(b->p==nil)
+		return 0;
+	while(b->p<b->ep){
+		c = *b->p++;
+		v |= (c & 0x7F)<<nb;
+		nb += 7;
+		if(!(c&0x80))
+			break;
+	}
+	if(v&(1<<(nb-1)))
+		v |= ~(((ulong)1<<nb)-1);
+	if(nb > 8*sizeof(ulong)){
+		if(0)
+		if(++nbad == 1)
+			fprint(2, "dwarf: overflow during parsing of sleb128 integer: got %d bits\n", nb);
+	}
+	return v;
+}
+