From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Tue, 19 Feb 2019 01:46:58 +0000 (+0100)
Subject: Generalise some printing primitives
X-Git-Tag: v5.0~47
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d8b3dd301477bfdfcca764ae4ff2afc3d04f8d2a;p=strace

Generalise some printing primitives

Character class checks and hexadecimal number formatting are open-coded
all over the place, let's try to de-duplicate them a bit.

* print_utils.h: New file.
* Makefile.am (strace_SOURCES): Add it.
* util.c: Include "print_utils.h".
(string_quote, dumpstr): Use sprint_byte_hex and is_print.
* v4l2.c: Include "print_utils.h".
(print_pixelformat): Use is_print and BYTE_HEX_CHARS_PRINTF_QUOTED,
add a note that the routine is rather generic.
---

diff --git a/Makefile.am b/Makefile.am
index c2b7ee10..0e26296f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -243,6 +243,7 @@ strace_SOURCES =	\
 	print_timespec.c \
 	print_timeval.c	\
 	print_timex.c	\
+	print_utils.h	\
 	printmode.c	\
 	printrusage.c	\
 	printsiginfo.c	\
diff --git a/print_utils.h b/print_utils.h
new file mode 100644
index 00000000..519cd401
--- /dev/null
+++ b/print_utils.h
@@ -0,0 +1,39 @@
+#ifndef STRACE_PRINT_UTILS_H
+# define STRACE_PRINT_UTILS_H
+
+# include <inttypes.h>
+
+/* Hexadecimal output utils */
+
+static const char hex_chars[16] = "0123456789abcdef";
+
+/**
+ * Character array representing hexadecimal encoding of a character value.
+ *
+ * @param b_ Byte to provide representation for.
+ */
+# define BYTE_HEX_CHARS(b_) \
+	hex_chars[((uint8_t) (b_)) >> 4], hex_chars[((uint8_t) (b_)) & 0xf]
+# define BYTE_HEX_CHARS_PRINTF(b_) \
+	'\\', 'x', BYTE_HEX_CHARS(b_)
+# define BYTE_HEX_CHARS_PRINTF_QUOTED(b_) \
+	'\'', BYTE_HEX_CHARS_PRINTF(b_), '\''
+
+static inline char *
+sprint_byte_hex(char *buf, uint8_t val)
+{
+	*buf++ = hex_chars[val >> 4];
+	*buf++ = hex_chars[val & 0xf];
+
+	return buf;
+}
+
+/* Character classification utils */
+
+static inline bool
+is_print(uint8_t c)
+{
+	return (c >= ' ') && (c < 0x7f);
+}
+
+#endif /* STRACE_PRINT_UTILS_H */
diff --git a/util.c b/util.c
index f0c7c6ae..239e0f13 100644
--- a/util.c
+++ b/util.c
@@ -24,6 +24,7 @@
 #include <sys/uio.h>
 
 #include "largefile_wrappers.h"
+#include "print_utils.h"
 #include "xlat.h"
 #include "xstring.h"
 
@@ -490,7 +491,7 @@ string_quote(const char *instr, char *outstr, const unsigned int size,
 	char *s = outstr;
 	unsigned int i;
 	int usehex, c, eol;
-	bool escape;
+	bool printable;
 
 	if (style & QUOTE_0_TERMINATED)
 		eol = '\0';
@@ -538,8 +539,7 @@ string_quote(const char *instr, char *outstr, const unsigned int size,
 				goto asciz_ended;
 			*s++ = '\\';
 			*s++ = 'x';
-			*s++ = "0123456789abcdef"[c >> 4];
-			*s++ = "0123456789abcdef"[c & 0xf];
+			s = sprint_byte_hex(s, c);
 		}
 
 		goto string_ended;
@@ -579,12 +579,12 @@ string_quote(const char *instr, char *outstr, const unsigned int size,
 			*s++ = 'v';
 			break;
 		default:
-			escape = (c < ' ') || (c > 0x7e);
+			printable = is_print(c);
 
-			if (!escape && escape_chars)
-				escape = !!strchr(escape_chars, c);
+			if (printable && escape_chars)
+				printable = !strchr(escape_chars, c);
 
-			if (!escape) {
+			if (printable) {
 				*s++ = c;
 			} else {
 				/* Print \octal */
@@ -942,8 +942,7 @@ dumpstr(struct tcb *const tcp, const kernel_ulong_t addr, const int len)
 		/* Hex dump */
 		do {
 			if (i < len) {
-				*dst++ = "0123456789abcdef"[*src >> 4];
-				*dst++ = "0123456789abcdef"[*src & 0xf];
+				dst = sprint_byte_hex(dst, *src);
 			} else {
 				*dst++ = ' ';
 				*dst++ = ' ';
@@ -958,7 +957,7 @@ dumpstr(struct tcb *const tcp, const kernel_ulong_t addr, const int len)
 		i -= 16;
 		src -= 16;
 		do {
-			if (*src >= ' ' && *src < 0x7f)
+			if (is_print(*src))
 				*dst++ = *src;
 			else
 				*dst++ = '.';
diff --git a/v4l2.c b/v4l2.c
index edc06f2f..b87ea333 100644
--- a/v4l2.c
+++ b/v4l2.c
@@ -42,6 +42,7 @@ typedef struct v4l2_standard struct_v4l2_standard;
 #include MPERS_DEFS
 
 #include "print_fields.h"
+#include "print_utils.h"
 #include "xstring.h"
 
 /* v4l2_fourcc_be was added by Linux commit v3.18-rc1~101^2^2~127 */
@@ -70,6 +71,7 @@ print_pixelformat(uint32_t fourcc, const struct xlat *xlat)
 	unsigned int i;
 
 	tprints("v4l2_fourcc(");
+	/* Generic char array printing routine.  */
 	for (i = 0; i < ARRAY_SIZE(a); ++i) {
 		unsigned char c = a[i];
 
@@ -84,7 +86,7 @@ print_pixelformat(uint32_t fourcc, const struct xlat *xlat)
 				'\0'
 			};
 			tprints(sym);
-		} else if (c >= ' ' && c <= 0x7e) {
+		} else if (is_print(c)) {
 			char sym[] = {
 				'\'',
 				c,
@@ -94,12 +96,7 @@ print_pixelformat(uint32_t fourcc, const struct xlat *xlat)
 			tprints(sym);
 		} else {
 			char hex[] = {
-				'\'',
-				'\\',
-				'x',
-				"0123456789abcdef"[c >> 4],
-				"0123456789abcdef"[c & 0xf],
-				'\'',
+				BYTE_HEX_CHARS_PRINTF_QUOTED(c),
 				'\0'
 			};
 			tprints(hex);