1 // SPDX-License-Identifier: GPL-2.0 2 #include "debug.h" 3 #include "util.h" 4 #include <linux/kernel.h> 5 #include <errno.h> 6 7 /* 8 * Used as the default ->buf value, so that people can always assume 9 * buf is non NULL and ->buf is NUL terminated even for a freshly 10 * initialized strbuf. 11 */ 12 char strbuf_slopbuf[1]; 13 14 int strbuf_init(struct strbuf *sb, ssize_t hint) 15 { 16 sb->alloc = sb->len = 0; 17 sb->buf = strbuf_slopbuf; 18 if (hint) 19 return strbuf_grow(sb, hint); 20 return 0; 21 } 22 23 void strbuf_release(struct strbuf *sb) 24 { 25 if (sb->alloc) { 26 zfree(&sb->buf); 27 strbuf_init(sb, 0); 28 } 29 } 30 31 char *strbuf_detach(struct strbuf *sb, size_t *sz) 32 { 33 char *res = sb->alloc ? sb->buf : NULL; 34 if (sz) 35 *sz = sb->len; 36 strbuf_init(sb, 0); 37 return res; 38 } 39 40 int strbuf_grow(struct strbuf *sb, size_t extra) 41 { 42 char *buf; 43 size_t nr = sb->len + extra + 1; 44 45 if (nr < sb->alloc) 46 return 0; 47 48 if (nr <= sb->len) 49 return -E2BIG; 50 51 if (alloc_nr(sb->alloc) > nr) 52 nr = alloc_nr(sb->alloc); 53 54 /* 55 * Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is 56 * a static variable. Thus we have to avoid passing it to realloc. 57 */ 58 buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf)); 59 if (!buf) 60 return -ENOMEM; 61 62 sb->buf = buf; 63 sb->alloc = nr; 64 return 0; 65 } 66 67 int strbuf_addch(struct strbuf *sb, int c) 68 { 69 int ret = strbuf_grow(sb, 1); 70 if (ret) 71 return ret; 72 73 sb->buf[sb->len++] = c; 74 sb->buf[sb->len] = '\0'; 75 return 0; 76 } 77 78 int strbuf_add(struct strbuf *sb, const void *data, size_t len) 79 { 80 int ret = strbuf_grow(sb, len); 81 if (ret) 82 return ret; 83 84 memcpy(sb->buf + sb->len, data, len); 85 return strbuf_setlen(sb, sb->len + len); 86 } 87 88 static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap) 89 { 90 int len, ret; 91 va_list ap_saved; 92 93 if (!strbuf_avail(sb)) { 94 ret = strbuf_grow(sb, 64); 95 if (ret) 96 return ret; 97 } 98 99 va_copy(ap_saved, ap); 100 len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap); 101 if (len < 0) 102 return len; 103 if (len > strbuf_avail(sb)) { 104 ret = strbuf_grow(sb, len); 105 if (ret) 106 return ret; 107 len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved); 108 va_end(ap_saved); 109 if (len > strbuf_avail(sb)) { 110 pr_debug("this should not happen, your vsnprintf is broken"); 111 return -EINVAL; 112 } 113 } 114 return strbuf_setlen(sb, sb->len + len); 115 } 116 117 int strbuf_addf(struct strbuf *sb, const char *fmt, ...) 118 { 119 va_list ap; 120 int ret; 121 122 va_start(ap, fmt); 123 ret = strbuf_addv(sb, fmt, ap); 124 va_end(ap); 125 return ret; 126 } 127 128 ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint) 129 { 130 size_t oldlen = sb->len; 131 size_t oldalloc = sb->alloc; 132 int ret; 133 134 ret = strbuf_grow(sb, hint ? hint : 8192); 135 if (ret) 136 return ret; 137 138 for (;;) { 139 ssize_t cnt; 140 141 cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1); 142 if (cnt < 0) { 143 if (oldalloc == 0) 144 strbuf_release(sb); 145 else 146 strbuf_setlen(sb, oldlen); 147 return cnt; 148 } 149 if (!cnt) 150 break; 151 sb->len += cnt; 152 ret = strbuf_grow(sb, 8192); 153 if (ret) 154 return ret; 155 } 156 157 sb->buf[sb->len] = '\0'; 158 return sb->len - oldlen; 159 } 160