diff options
Diffstat (limited to 'strbuf.h')
| -rw-r--r-- | strbuf.h | 86 |
1 files changed, 84 insertions, 2 deletions
@@ -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 */ |