Add support for tracing fork children

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 189 insertions, 0 deletions

diff --git a/memory.c b/memory.c
new file mode 100644
index 0000000..1af854f
--- /dev/null
+++ b/memory.c
@@ -0,0 +1,189 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+char *
+get_string(pid_t pid, unsigned long int addr, size_t *lenp, const char **errorp)
+{
+	struct iovec inv, outv;
+	size_t off = 0, size = 0, page_off, read_size;
+	char *out = NULL, *in = (char *)addr, *p;
+	page_off = (size_t)addr % sizeof(PAGE_SIZE);
+	read_size = PAGE_SIZE - page_off;
+	*errorp = NULL;
+	for (;; read_size = PAGE_SIZE) {
+		out = realloc(out, size + PAGE_SIZE);
+		if (!out)
+			eprintf("realloc:");
+		inv.iov_base  = &in[off];
+		inv.iov_len   = read_size;
+		outv.iov_base = &out[off];
+		outv.iov_len  = read_size;
+		if (process_vm_readv(pid, &outv, 1, &inv, 1, 0) != (ssize_t)read_size) {
+			*errorp = errno == EFAULT ? "<invalid address>" : "<an error occured during reading of string>";
+			*lenp = 0;
+			return 0;
+		}
+		p = memchr(&out[off], 0, read_size);
+		if (p) {
+			*lenp = (size_t)(p - out);
+			return out;
+		}
+		off += read_size;
+	}
+}
+
+
+int
+get_struct(pid_t pid, unsigned long int addr, void *out, size_t size, const char **errorp)
+{
+	struct iovec inv, outv;
+	*errorp = NULL;
+	inv.iov_base  = (void *)addr;
+	inv.iov_len   = size;
+	outv.iov_base = out;
+	outv.iov_len  = size;
+	if (process_vm_readv(pid, &outv, 1, &inv, 1, 0) == (ssize_t)size)
+		return 0;
+	*errorp = errno == EFAULT ? "<invalid address>" : "<an error occured during reading of string>";
+	return -1;
+}
+
+
+char *
+get_memory(pid_t pid, unsigned long int addr, size_t n, const char **errorp)
+{
+	char *out = malloc(n + (size_t)!n);
+	if (!out)
+		eprintf("malloc:");
+	if (get_struct(pid, addr, out, n, errorp)) {
+		free(out);
+		return NULL;
+	}
+	return out;
+}
+
+
+
+static void
+add_char(char **strp, size_t *sizep, size_t *lenp, char c)
+{
+	if (*lenp == *sizep) {
+		*strp = realloc(*strp, *sizep += 128);
+		if (!*strp)
+			eprintf("realloc:");
+	}
+	(*strp)[(*lenp)++] = c;
+}
+
+
+static size_t
+utf8len(char *str)
+{
+	size_t ext, i, len;
+	uint32_t code;
+	uint8_t *s = (uint8_t *)str;
+
+	struct {
+		uint8_t  lower;
+		uint8_t  upper;
+		uint8_t  mask;
+		uint32_t lowest;
+	} lookup[] = {
+		{ 0x00, 0x7F, 0x7F, UINT32_C(0x000000) },
+		{ 0xC0, 0xDF, 0x1F, UINT32_C(0x000080) },
+		{ 0xE0, 0xEF, 0x0F, UINT32_C(0x000800) },
+		{ 0xF0, 0xF7, 0x07, UINT32_C(0x010000) }
+	};
+
+	for (ext = 0; ext < sizeof(lookup) / sizeof(*lookup); ext++)
+		if (lookup[ext].lower <= s[0] && s[0] <= lookup[ext].upper)
+			goto found;
+	return 0;
+
+found:
+	code = s[0] & lookup[ext].mask;
+	len = ext + 1;
+	for (i = 1; i < len; i++) {
+		if ((s[i] & 0xC0) != 0x80)
+			return 0;
+		code = (code << 6) | (s[i] ^ 0x80);
+	}
+
+	if (code < lookup[ext].lowest || (0xD800 <= code && code <= 0xDFFF) || code > UINT32_C(0x10FFFF))
+		return 0;
+	return len;
+}
+
+
+char *
+escape_memory(char *str, size_t m)
+{
+	char *ret = NULL, *s, *end;
+	size_t size = 0;
+	size_t len = 0;
+	size_t n = 0;
+	int need_new_string = 0;
+	if (!str) {
+		str = strdup("NULL");
+		if (!str)
+			eprintf("strdup:");
+		return str;
+	}
+	add_char(&ret, &size, &len, '"');
+	for (s = str, end = &str[m]; s != end; s++) {
+		if (n) {
+			add_char(&ret, &size, &len, *s);
+			n -= 1;
+		} else if (*s == '\r') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 'r');
+		} else if (*s == '\t') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 't');
+		} else if (*s == '\a') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 'a');
+		} else if (*s == '\f') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 'f');
+		} else if (*s == '\v') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 'v');
+		} else if (*s == '\b') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 'b');
+		} else if (*s == '\n') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, 'n');
+		} else if (*s == '\"') {
+			add_char(&ret, &size, &len, '\\');
+			add_char(&ret, &size, &len, '"');
+		} else if (*s < ' ' || *s >= 127) {
+			n = utf8len(s);
+			if (n > 1) {
+				add_char(&ret, &size, &len, *s);
+				n -= 1;
+			} else {
+				n = 0;
+				add_char(&ret, &size, &len, '\\');
+				add_char(&ret, &size, &len, 'x');
+				add_char(&ret, &size, &len, "0123456789abcdef"[(int)*(unsigned char *)s >> 4]);
+				add_char(&ret, &size, &len, "0123456789abcdef"[(int)*(unsigned char *)s & 15]);
+				need_new_string = 1;
+				continue;
+			}
+		} else {
+			if (need_new_string && isxdigit(*s)) {
+				add_char(&ret, &size, &len, '"');
+				add_char(&ret, &size, &len, '"');
+			}
+			add_char(&ret, &size, &len, *s);
+		}
+		need_new_string = 0;
+	}
+	add_char(&ret, &size, &len, '"');
+	add_char(&ret, &size, &len, '\0');
+	free(str);
+	return ret;
+}