Hi,
This patch factors out new function read_string in dwarf.c.
Bootstrapped and reg-tested on x86_64.
OK for trunk (or, for stage1)?
Thanks,
- Tom
[libbacktrace] Factor out read_string
2018-11-15 Tom de Vries <tdevr...@suse.de>
* dwarf.c (read_string): Factor out of ...
(read_attribute, read_line_header, read_line_program): ... here.
---
libbacktrace/dwarf.c | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/libbacktrace/dwarf.c b/libbacktrace/dwarf.c
index 4566d37cf2f..c4f8732c7eb 100644
--- a/libbacktrace/dwarf.c
+++ b/libbacktrace/dwarf.c
@@ -411,6 +411,25 @@ advance (struct dwarf_buf *buf, size_t count)
return 1;
}
+/* Read one zero-terminated string from BUF and advance past the string. */
+
+static const char *
+read_string (struct dwarf_buf *buf)
+{
+ const char *p = (const char *)buf->buf;
+ size_t len = strnlen (p, buf->left);
+
+ /* - If len == left, we ran out of buffer before finding the zero terminator.
+ Generate an error by advancing len + 1.
+ - If len < left, advance by len + 1 to skip past the zero terminator. */
+ size_t count = len + 1;
+
+ if (!advance (buf, count))
+ return NULL;
+
+ return p;
+}
+
/* Read one byte from BUF and advance 1 byte. */
static unsigned char
@@ -694,8 +713,8 @@ read_attribute (enum dwarf_form form, struct dwarf_buf *buf,
return 1;
case DW_FORM_string:
val->encoding = ATTR_VAL_STRING;
- val->u.string = (const char *) buf->buf;
- return advance (buf, strnlen ((const char *) buf->buf, buf->left) + 1);
+ val->u.string = read_string (buf);
+ return val->u.string == NULL ? 0 : 1;
case DW_FORM_block:
val->encoding = ATTR_VAL_BLOCK;
return advance (buf, read_uleb128 (buf));
@@ -1649,11 +1668,10 @@ read_line_header (struct backtrace_state *state, struct
unit *u,
if (hdr_buf.reported_underflow)
return 0;
- hdr->dirs[i] = (const char *) hdr_buf.buf;
- ++i;
- if (!advance (&hdr_buf,
- strnlen ((const char *) hdr_buf.buf, hdr_buf.left) + 1))
+ hdr->dirs[i] = read_string (&hdr_buf);
+ if (hdr->dirs[i] == NULL)
return 0;
+ ++i;
}
if (!advance (&hdr_buf, 1))
return 0;
@@ -1687,9 +1705,8 @@ read_line_header (struct backtrace_state *state, struct
unit *u,
if (hdr_buf.reported_underflow)
return 0;
- filename = (const char *) hdr_buf.buf;
- if (!advance (&hdr_buf,
- strnlen ((const char *) hdr_buf.buf, hdr_buf.left) + 1))
+ filename = read_string (&hdr_buf);
+ if (filename == NULL)
return 0;
dir_index = read_uleb128 (&hdr_buf);
if (IS_ABSOLUTE_PATH (filename)
@@ -1808,8 +1825,8 @@ read_line_program (struct backtrace_state *state, struct
dwarf_data *ddata,
const char *f;
unsigned int dir_index;
- f = (const char *) line_buf->buf;
- if (!advance (line_buf, strnlen (f, line_buf->left) + 1))
+ f = read_string (line_buf);
+ if (f == NULL)
return 0;
dir_index = read_uleb128 (line_buf);
/* Ignore that time and length. */
