The gory details are explained in strbuf.h. The change of semantics this
patch enforces is that the embeded buffer has always a '\0' character after
its last byte, to always make it a C-string. The offs-by-one changes are all
related to that very change.
A strbuf can be used to store byte arrays, or as an extended string
library. The `buf' member can be passed to any C legacy string function,
because strbuf operations always ensure there is a terminating \0 at the end
of the buffer, not accounted in the `len' field of the structure.
A strbuf can be used to generate a string/buffer whose final size is not
really known, and then "strbuf_detach" can be used to get the built buffer,
and keep the wrapping "strbuf" structure usable for further work again.
Other interesting feature: strbuf_grow(sb, size) ensure that there is
enough allocated space in `sb' to put `size' new octets of data in the
buffer. It helps avoiding reallocating data for nothing when the problem the
strbuf helps to solve has a known typical size.
Signed-off-by: Pierre Habouzit <madcoder@xxxxxxxxxx>
---
archive-tar.c | 2 +-
fast-import.c | 15 ++++----
mktree.c | 4 +--
strbuf.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++--------
strbuf.h | 86 +++++++++++++++++++++++++++++++++++++++++++++++-
5 files changed, 181 insertions(+), 28 deletions(-)
diff --git a/archive-tar.c b/archive-tar.c
index 66fe3e3..a0763c5 100644
--- a/archive-tar.c
+++ b/archive-tar.c
@@ -166,7 +166,7 @@ static void write_entry(const unsigned char *sha1, struct strbuf *path,
sprintf(header.name, "%s.paxheader", sha1_to_hex(sha1));
} else {
if (verbose)
- fprintf(stderr, "%.*s\n", path->len, path->buf);
+ fprintf(stderr, "%.*s\n", (int)path->len, path->buf);
if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
*header.typeflag = TYPEFLAG_DIR;
mode = (mode | 0777) & ~tar_umask;
diff --git a/fast-import.c b/fast-import.c
index 078079d..2f7baf4 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1595,7 +1595,7 @@ static void read_next_command(void)
} else {
struct recent_command *rc;
- command_buf.buf = NULL;
+ strbuf_detach(&command_buf);
read_line(&command_buf, stdin, '\n');
if (command_buf.eof)
return;
@@ -1649,7 +1649,6 @@ static void *cmd_data (size_t *size)
size_t sz = 8192, term_len = command_buf.len - 5 - 2;
length = 0;
buffer = xmalloc(sz);
- command_buf.buf = NULL;
for (;;) {
read_line(&command_buf, stdin, '\n');
if (command_buf.eof)
@@ -1657,11 +1656,11 @@ static void *cmd_data (size_t *size)
if (term_len == command_buf.len
&& !strcmp(term, command_buf.buf))
break;
- ALLOC_GROW(buffer, length + command_buf.len, sz);
+ ALLOC_GROW(buffer, length + command_buf.len + 1, sz);
memcpy(buffer + length,
command_buf.buf,
- command_buf.len - 1);
- length += command_buf.len - 1;
+ command_buf.len);
+ length += command_buf.len;
buffer[length++] = '\n';
}
free(term);
@@ -2101,7 +2100,7 @@ static void cmd_new_commit(void)
}
/* file_change* */
- while (!command_buf.eof && command_buf.len > 1) {
+ while (!command_buf.eof && command_buf.len > 0) {
if (!prefixcmp(command_buf.buf, "M "))
file_change_m(b);
else if (!prefixcmp(command_buf.buf, "D "))
@@ -2256,7 +2255,7 @@ static void cmd_reset_branch(void)
else
b = new_branch(sp);
read_next_command();
- if (!cmd_from(b) && command_buf.len > 1)
+ if (!cmd_from(b) && command_buf.len > 0)
unread_command_buf = 1;
}
@@ -2273,7 +2272,7 @@ static void cmd_checkpoint(void)
static void cmd_progress(void)
{
- fwrite(command_buf.buf, 1, command_buf.len - 1, stdout);
+ fwrite(command_buf.buf, 1, command_buf.len, stdout);
fputc('\n', stdout);
fflush(stdout);
skip_optional_lf();
diff --git a/mktree.c b/mktree.c
index d86dde8..86de5eb 100644
--- a/mktree.c
+++ b/mktree.c
@@ -92,7 +92,6 @@ int main(int ac, char **av)
strbuf_init(&sb);
while (1) {
- int len;
char *ptr, *ntr;
unsigned mode;
enum object_type type;
@@ -101,7 +100,6 @@ int main(int ac, char **av)
read_line(&sb, stdin, line_termination);
if (sb.eof)
break;
- len = sb.len;
ptr = sb.buf;
/* Input is non-recursive ls-tree output format
* mode SP type SP sha1 TAB name
@@ -111,7 +109,7 @@ int main(int ac, char **av)
die("input format error: %s", sb.buf);
ptr = ntr + 1; /* type */
ntr = strchr(ptr, ' ');
- if (!ntr || sb.buf + len <= ntr + 41 ||
+ if (!ntr || sb.buf + sb.len <= ntr + 40 ||
ntr[41] != '\t' ||
get_sha1_hex(ntr + 1, sha1))
die("input format error: %s", sb.buf);
diff --git a/strbuf.c b/strbuf.c
index e33d06b..acc7fc8 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -2,40 +2,114 @@
#include "strbuf.h"
void strbuf_init(struct strbuf *sb) {
- sb->buf = NULL;
- sb->eof = sb->alloc = sb->len = 0;
+ memset(sb, 0, sizeof(*sb));
}
-static void strbuf_begin(struct strbuf *sb) {
+void strbuf_release(struct strbuf *sb) {
free(sb->buf);
+ memset(sb, 0, sizeof(*sb));
+}
+
+void strbuf_reset(struct strbuf *sb) {
+ if (sb->len)
+ strbuf_setlen(sb, 0);
+ sb->eof = 0;
+}
+
+char *strbuf_detach(struct strbuf *sb) {
+ char *res = sb->buf;
strbuf_init(sb);
+ return res;
+}
+
+void strbuf_grow(struct strbuf *sb, size_t extra) {
+ if (sb->len + extra + 1 <= sb->len)
+ die("you want to use way too much memory");
+ ALLOC_GROW(sb->buf, sb->len + extra + 1, sb->alloc);
}
-static void inline strbuf_add(struct strbuf *sb, int ch) {
- if (sb->alloc <= sb->len) {
- sb->alloc = sb->alloc * 3 / 2 + 16;
- sb->buf = xrealloc(sb->buf, sb->alloc);
+void strbuf_add(struct strbuf *sb, const void *data, size_t len) {
+ strbuf_grow(sb, len);
+ memcpy(sb->buf + sb->len, data, len);
+ strbuf_setlen(sb, sb->len + len);
+}
+
+void strbuf_addf(struct strbuf *sb, const char *fmt, ...) {
+ int len;
+ va_list ap;
+
+ va_start(ap, fmt);
+ len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
+ va_end(ap);
+ if (len < 0) {
+ len = 0;
}
- sb->buf[sb->len++] = ch;
+ if (len >= strbuf_avail(sb)) {
+ strbuf_grow(sb, len);
+ va_start(ap, fmt);
+ len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
+ va_end(ap);
+ if (len >= strbuf_avail(sb)) {
+ die("this should not happen, your snprintf is broken");
+ }
+ }
+ strbuf_setlen(sb, sb->len + len);
}
-static void strbuf_end(struct strbuf *sb) {
- strbuf_add(sb, 0);
+size_t strbuf_fread(struct strbuf *sb, size_t size, FILE *f) {
+ size_t res;
+
+ strbuf_grow(sb, size);
+ res = fread(sb->buf + sb->len, 1, size, f);
+ if (res > 0) {
+ strbuf_setlen(sb, sb->len + res);
+ }
+ return res;
+}
+
+ssize_t strbuf_read(struct strbuf *sb, int fd)
+{
+ size_t oldlen = sb->len;
+
+ for (;;) {
+ ssize_t cnt;
+
+ strbuf_grow(sb, 8192);
+ cnt = xread(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
+ if (cnt < 0) {
+ strbuf_setlen(sb, oldlen);
+ return -1;
+ }
+ if (!cnt)
+ break;
+ sb->len += cnt;
+ }
+
+ sb->buf[sb->len] = '\0';
+ return sb->len - oldlen;
}
void read_line(struct strbuf *sb, FILE *fp, int term) {
int ch;
- strbuf_begin(sb);
if (feof(fp)) {
+ strbuf_release(sb);
sb->eof = 1;
return;
}
+
+ strbuf_reset(sb);
while ((ch = fgetc(fp)) != EOF) {
if (ch == term)
break;
- strbuf_add(sb, ch);
+ strbuf_grow(sb, 1);
+ sb->buf[sb->len++] = ch;
}
- if (ch == EOF && sb->len == 0)
+ if (ch == EOF && sb->len == 0) {
+ strbuf_release(sb);
sb->eof = 1;
- strbuf_end(sb);
+ }
+
+ strbuf_grow(sb, 1);
+ sb->buf[sb->len] = '\0';
}
+
diff --git a/strbuf.h b/strbuf.h
index 74cc012..b40dc99 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -1,13 +1,95 @@
#ifndef STRBUF_H
#define STRBUF_H
+
+/*
+ * Strbuf's can be use in many ways: as a byte array, or to store arbitrary
+ * long, overflow safe strings.
+ *
+ * Strbufs has some invariants that are very important to keep in mind:
+ *
+ * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to
+ * build complex strings/buffers whose final size isn't easily known.
+ *
+ * It is legal to copy the ->buf pointer away. Though if you want to reuse
+ * the strbuf after that, setting ->buf to NULL isn't legal.
+ * `strbuf_detach' is the operation that detachs a buffer from its shell
+ * while keeping the shell valid wrt its invariants.
+ *
+ * 2. the ->buf member is a byte array that has at least ->len + 1 bytes
+ * allocated. The extra byte is used to store a '\0', allowing the ->buf
+ * member to be a valid C-string. Every strbuf function ensure this
+ * invariant is preserved.
+ *
+ * Note that it is OK to "play" with the buffer directly if you work it
+ * that way:
+ *
+ * strbuf_grow(sb, SOME_SIZE);
+ * // ... here the memory areay starting at sb->buf, and of length
+ * // sb_avail(sb) is all yours, and you are sure that sb_avail(sb) is at
+ * // least SOME_SIZE
+ * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE);
+ *
+ * Of course, SOME_OTHER_SIZE must be smaller or equal to sb_avail(sb).
+ *
+ * Doing so is safe, though if it has to be done in many places, adding the
+ * missing API to the strbuf module is the way to go.
+ *
+ * XXX: do _not_ assume that the area that is yours is of size ->alloc - 1
+ * even if it's true in the current implementation. Alloc is somehow a
+ * "private" member that should not be messed with.
+ */
+
+#include <assert.h>
+
struct strbuf {
- int alloc;
- int len;
+ size_t alloc;
+ size_t len;
int eof;
char *buf;
};
+#define STRBUF_INIT { 0, 0, 0, NULL }
+
+/*----- strbuf life cycle -----*/
extern void strbuf_init(struct strbuf *);
+extern void strbuf_release(struct strbuf *);
+extern void strbuf_reset(struct strbuf *);
+extern char *strbuf_detach(struct strbuf *);
+
+/*----- strbuf size related -----*/
+static inline size_t strbuf_avail(struct strbuf *sb) {
+ return sb->alloc ? sb->alloc - sb->len - 1 : 0;
+}
+static inline void strbuf_setlen(struct strbuf *sb, size_t len) {
+ assert (len < sb->alloc);
+ sb->len = len;
+ sb->buf[len] = '\0';
+}
+
+extern void strbuf_grow(struct strbuf *, size_t);
+
+/*----- add data in your buffer -----*/
+static inline void strbuf_addch(struct strbuf *sb, int c) {
+ strbuf_grow(sb, 1);
+ sb->buf[sb->len++] = c;
+ sb->buf[sb->len] = '\0';
+}
+
+extern void strbuf_add(struct strbuf *, const void *, size_t);
+static inline void strbuf_addstr(struct strbuf *sb, const char *s) {
+ strbuf_add(sb, s, strlen(s));
+}
+static inline void strbuf_addbuf(struct strbuf *sb, struct strbuf *sb2) {
+ strbuf_add(sb, sb2->buf, sb2->len);
+}
+
+__attribute__((format(printf,2,3)))
+extern void strbuf_addf(struct strbuf *sb, const char *fmt, ...);
+
+extern size_t strbuf_fread(struct strbuf *, size_t, FILE *);
+/* XXX: if read fails, any partial read is undone */
+extern ssize_t strbuf_read(struct strbuf *, int fd);
+
extern void read_line(struct strbuf *, FILE *, int);
#endif /* STRBUF_H */
--
1.5.3.1
-
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