From b449f4cfc972929b638b90d375b8960c37790618 Mon Sep 17 00:00:00 2001 From: Pierre Habouzit Date: Thu, 6 Sep 2007 13:20:05 +0200 Subject: [PATCH] Rework strbuf API and semantics. 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 Signed-off-by: Junio C Hamano --- archive-tar.c | 2 +- fast-import.c | 15 ++++---- mktree.c | 4 +- strbuf.c | 101 +++++++++++++++++++++++++++++++++++++++++++------- strbuf.h | 86 +++++++++++++++++++++++++++++++++++++++++- 5 files changed, 180 insertions(+), 28 deletions(-) diff --git a/archive-tar.c b/archive-tar.c index 66fe3e375..a0763c5b5 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 078079d40..2f7baf491 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 d86dde89d..86de5eb5f 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 e33d06b87..7136de14c 100644 --- a/strbuf.c +++ b/strbuf.c @@ -2,40 +2,113 @@ #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); +} + +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; + } + 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 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); +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); } - sb->buf[sb->len++] = ch; + return res; } -static void strbuf_end(struct strbuf *sb) { - strbuf_add(sb, 0); +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 74cc012c2..b40dc99fd 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 + 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 */ -- 2.26.2