1 #ifndef __PERF_STRBUF_H 2 #define __PERF_STRBUF_H 3 4 /* 5 * Strbuf's can be use in many ways: as a byte array, or to store arbitrary 6 * long, overflow safe strings. 7 * 8 * Strbufs has some invariants that are very important to keep in mind: 9 * 10 * 1. the ->buf member is always malloc-ed, hence strbuf's can be used to 11 * build complex strings/buffers whose final size isn't easily known. 12 * 13 * It is NOT legal to copy the ->buf pointer away. 14 * `strbuf_detach' is the operation that detachs a buffer from its shell 15 * while keeping the shell valid wrt its invariants. 16 * 17 * 2. the ->buf member is a byte array that has at least ->len + 1 bytes 18 * allocated. The extra byte is used to store a '\0', allowing the ->buf 19 * member to be a valid C-string. Every strbuf function ensure this 20 * invariant is preserved. 21 * 22 * Note that it is OK to "play" with the buffer directly if you work it 23 * that way: 24 * 25 * strbuf_grow(sb, SOME_SIZE); 26 * ... Here, the memory array starting at sb->buf, and of length 27 * ... strbuf_avail(sb) is all yours, and you are sure that 28 * ... strbuf_avail(sb) is at least SOME_SIZE. 29 * strbuf_setlen(sb, sb->len + SOME_OTHER_SIZE); 30 * 31 * Of course, SOME_OTHER_SIZE must be smaller or equal to strbuf_avail(sb). 32 * 33 * Doing so is safe, though if it has to be done in many places, adding the 34 * missing API to the strbuf module is the way to go. 35 * 36 * XXX: do _not_ assume that the area that is yours is of size ->alloc - 1 37 * even if it's true in the current implementation. Alloc is somehow a 38 * "private" member that should not be messed with. 39 */ 40 41 #include <assert.h> 42 #include <stdarg.h> 43 44 extern char strbuf_slopbuf[]; 45 struct strbuf { 46 size_t alloc; 47 size_t len; 48 char *buf; 49 }; 50 51 #define STRBUF_INIT { 0, 0, strbuf_slopbuf } 52 53 /*----- strbuf life cycle -----*/ 54 int strbuf_init(struct strbuf *buf, ssize_t hint); 55 void strbuf_release(struct strbuf *buf); 56 char *strbuf_detach(struct strbuf *buf, size_t *); 57 58 /*----- strbuf size related -----*/ 59 static inline ssize_t strbuf_avail(const struct strbuf *sb) { 60 return sb->alloc ? sb->alloc - sb->len - 1 : 0; 61 } 62 63 int strbuf_grow(struct strbuf *buf, size_t); 64 65 static inline int strbuf_setlen(struct strbuf *sb, size_t len) { 66 int ret; 67 if (!sb->alloc) { 68 ret = strbuf_grow(sb, 0); 69 if (ret) 70 return ret; 71 } 72 assert(len < sb->alloc); 73 sb->len = len; 74 sb->buf[len] = '\0'; 75 return 0; 76 } 77 78 /*----- add data in your buffer -----*/ 79 int strbuf_addch(struct strbuf *sb, int c); 80 81 int strbuf_add(struct strbuf *buf, const void *, size_t); 82 static inline int strbuf_addstr(struct strbuf *sb, const char *s) { 83 return strbuf_add(sb, s, strlen(s)); 84 } 85 86 __attribute__((format(printf,2,3))) 87 int strbuf_addf(struct strbuf *sb, const char *fmt, ...); 88 89 /* XXX: if read fails, any partial read is undone */ 90 ssize_t strbuf_read(struct strbuf *, int fd, ssize_t hint); 91 92 #endif /* __PERF_STRBUF_H */ 93