1 // SPDX-License-Identifier: GPL-2.0 2 #include "debug.h" 3 #include <linux/kernel.h> 4 #include <linux/zalloc.h> 5 #include <errno.h> 6 #include <stdlib.h> 7 #include <unistd.h> 8 9 /* 10 * Used as the default ->buf value, so that people can always assume 11 * buf is non NULL and ->buf is NUL terminated even for a freshly 12 * initialized strbuf. 13 */ 14 char strbuf_slopbuf[1]; 15 16 int strbuf_init(struct strbuf *sb, ssize_t hint) 17 { 18 sb->alloc = sb->len = 0; 19 sb->buf = strbuf_slopbuf; 20 if (hint) 21 return strbuf_grow(sb, hint); 22 return 0; 23 } 24 25 void strbuf_release(struct strbuf *sb) 26 { 27 if (sb->alloc) { 28 zfree(&sb->buf); 29 strbuf_init(sb, 0); 30 } 31 } 32 33 char *strbuf_detach(struct strbuf *sb, size_t *sz) 34 { 35 char *res = sb->alloc ? sb->buf : NULL; 36 if (sz) 37 *sz = sb->len; 38 strbuf_init(sb, 0); 39 return res; 40 } 41 42 int strbuf_grow(struct strbuf *sb, size_t extra) 43 { 44 char *buf; 45 size_t nr = sb->len + extra + 1; 46 47 if (nr < sb->alloc) 48 return 0; 49 50 if (nr <= sb->len) 51 return -E2BIG; 52 53 if (alloc_nr(sb->alloc) > nr) 54 nr = alloc_nr(sb->alloc); 55 56 /* 57 * Note that sb->buf == strbuf_slopbuf if sb->alloc == 0, and it is 58 * a static variable. Thus we have to avoid passing it to realloc. 59 */ 60 buf = realloc(sb->alloc ? sb->buf : NULL, nr * sizeof(*buf)); 61 if (!buf) 62 return -ENOMEM; 63 64 sb->buf = buf; 65 sb->alloc = nr; 66 return 0; 67 } 68 69 int strbuf_addch(struct strbuf *sb, int c) 70 { 71 int ret = strbuf_grow(sb, 1); 72 if (ret) 73 return ret; 74 75 sb->buf[sb->len++] = c; 76 sb->buf[sb->len] = '\0'; 77 return 0; 78 } 79 80 int strbuf_add(struct strbuf *sb, const void *data, size_t len) 81 { 82 int ret = strbuf_grow(sb, len); 83 if (ret) 84 return ret; 85 86 memcpy(sb->buf + sb->len, data, len); 87 return strbuf_setlen(sb, sb->len + len); 88 } 89 90 static int strbuf_addv(struct strbuf *sb, const char *fmt, va_list ap) 91 { 92 int len, ret; 93 va_list ap_saved; 94 95 if (!strbuf_avail(sb)) { 96 ret = strbuf_grow(sb, 64); 97 if (ret) 98 return ret; 99 } 100 101 va_copy(ap_saved, ap); 102 len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap); 103 if (len < 0) { 104 va_end(ap_saved); 105 return len; 106 } 107 if (len > strbuf_avail(sb)) { 108 ret = strbuf_grow(sb, len); 109 if (ret) { 110 va_end(ap_saved); 111 return ret; 112 } 113 len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap_saved); 114 if (len > strbuf_avail(sb)) { 115 pr_debug("this should not happen, your vsnprintf is broken"); 116 va_end(ap_saved); 117 return -EINVAL; 118 } 119 } 120 va_end(ap_saved); 121 return strbuf_setlen(sb, sb->len + len); 122 } 123 124 int strbuf_addf(struct strbuf *sb, const char *fmt, ...) 125 { 126 va_list ap; 127 int ret; 128 129 va_start(ap, fmt); 130 ret = strbuf_addv(sb, fmt, ap); 131 va_end(ap); 132 return ret; 133 } 134 135 ssize_t strbuf_read(struct strbuf *sb, int fd, ssize_t hint) 136 { 137 size_t oldlen = sb->len; 138 size_t oldalloc = sb->alloc; 139 int ret; 140 141 ret = strbuf_grow(sb, hint ? hint : 8192); 142 if (ret) 143 return ret; 144 145 for (;;) { 146 ssize_t cnt; 147 148 cnt = read(fd, sb->buf + sb->len, sb->alloc - sb->len - 1); 149 if (cnt < 0) { 150 if (oldalloc == 0) 151 strbuf_release(sb); 152 else 153 strbuf_setlen(sb, oldlen); 154 return cnt; 155 } 156 if (!cnt) 157 break; 158 sb->len += cnt; 159 ret = strbuf_grow(sb, 8192); 160 if (ret) 161 return ret; 162 } 163 164 sb->buf[sb->len] = '\0'; 165 return sb->len - oldlen; 166 } 167