diff options
Diffstat (limited to 'utils.c')
| -rw-r--r-- | utils.c | 171 |
1 files changed, 171 insertions, 0 deletions
@@ -0,0 +1,171 @@ +/* + * utils.c - Some helper code for debugging and error logging. + */ +#include "utils.h" + +/* + * Helper function to skip past all spaces (and comments) + * Returns a pointer to the first non-space character. + */ +const char *after_spaces(const char *str) +{ + // Skip whitespace and comments: + skip_whitespace: + switch (*str) { + case ' ': case '\r': case '\n': case '\t': { + ++str; + goto skip_whitespace; + } + case '#': { + while (*str && *str != '\n') ++str; + goto skip_whitespace; + } + } + return str; +} + +/* + * Return the first character after a valid BPEG name, or NULL if none is + * found. + */ +const char *after_name(const char *str) +{ + if (*str == '^' || *str == '_' || *str == '$') { + return (str[1] == *str) ? &str[2] : &str[1]; + } + if (!isalpha(*str)) return NULL; + for (++str; *str; ++str) { + if (!(isalnum(*str) || *str == '-')) + break; + } + return str; +} + +/* + * Check if a character is found and if so, move past it. + */ +int matchchar(const char **str, char c) +{ + *str = after_spaces(*str); + if (**str == c) { + ++(*str); + return 1; + } else { + return 0; + } +} + +/* + * Process a string escape sequence for a character and return the + * character that was escaped. + * Set *end = the first character past the end of the escape sequence. + */ +char unescapechar(const char *escaped, const char **end) +{ + size_t len = 1; + char ret = *escaped; + switch (*escaped) { + case 'a': ret = '\a'; break; case 'b': ret = '\b'; break; + case 'n': ret = '\n'; break; case 'r': ret = '\r'; break; + case 't': ret = '\t'; break; case 'v': ret = '\v'; break; + case 'e': ret = '\033'; break; + case 'x': { // Hex + static const char hextable[255] = { + ['0']=0x10, ['1']=0x1, ['2']=0x2, ['3']=0x3, ['4']=0x4, + ['5']=0x5, ['6']=0x6, ['7']=0x7, ['8']=0x8, ['9']=0x9, + ['a']=0xa, ['b']=0xb, ['c']=0xc, ['d']=0xd, ['e']=0xe, ['f']=0xf, + ['A']=0xa, ['B']=0xb, ['C']=0xc, ['D']=0xd, ['E']=0xe, ['F']=0xf, + }; + if (hextable[(int)escaped[1]] && hextable[(int)escaped[2]]) { + ret = (hextable[(int)escaped[1]] << 4) | (hextable[(int)escaped[2]] & 0xF); + len = 3; + } + break; + } + case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': { // Octal + ret = escaped[0] - '0'; + if ('0' <= escaped[1] && escaped[1] <= '7') { + ++len; + ret = (ret << 3) | (escaped[1] - '0'); + if ('0' <= escaped[2] && escaped[2] <= '7') { + ++len; + ret = (ret << 3) | (escaped[2] - '0'); + } + } + break; + } + default: break; + } + *end = &escaped[len]; + return ret; +} + +/* + * Write an unescaped version of `src` to `dest` (at most bufsize-1 chars, + * terminated by a null byte) + */ +size_t unescape_string(char *dest, const char *src, size_t bufsize) +{ + size_t len = 0; +#define PUT(c) do { *(dest++) = (char)(c); ++len; } while (0) + for ( ; *src && len < bufsize; ++src) { + if (*src != '\\') { + PUT(*src); + continue; + } + ++src; + switch (*src) { + case 'a': PUT('\a'); break; case 'b': PUT('\b'); break; + case 'n': PUT('\n'); break; case 'r': PUT('\r'); break; + case 't': PUT('\t'); break; case 'v': PUT('\v'); break; + case 'e': PUT('\033'); break; + case 'x': { // Hex + static const char hextable[255] = { + ['0']=0x10, ['1']=0x1, ['2']=0x2, ['3']=0x3, ['4']=0x4, + ['5']=0x5, ['6']=0x6, ['7']=0x7, ['8']=0x8, ['9']=0x9, + ['a']=0xa, ['b']=0xb, ['c']=0xc, ['d']=0xd, ['e']=0xe, ['f']=0xf, + ['A']=0xa, ['B']=0xb, ['C']=0xc, ['D']=0xd, ['E']=0xe, ['F']=0xf, + }; + if (hextable[(int)src[1]] && hextable[(int)src[2]]) { + PUT((hextable[(int)src[1]] << 4) | (hextable[(int)src[2]] & 0xF)); + src += 2; + } + break; + } + case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': { // Octal + int c = *src - '0'; + if ('0' <= src[1] && src[1] <= '7') { + ++src; + c = (c << 3) | (*src - '0'); + if ('0' <= src[1] && src[1] <= '7' && (c << 3) < 256) { + ++src; + c = (c << 3) | (*src - '0'); + } + } + PUT(c); + break; + } + default: PUT(*src); break; + } + } + *dest = '\0'; + return len; +#undef PUT +} + +/* + * Read an entire file into memory. + */ +char *readfile(int fd) +{ + size_t capacity = 1000, len = 0; + char *buf = calloc(sizeof(char), capacity+1); + ssize_t just_read; + while ((just_read=read(fd, &buf[len], capacity-len)) > 0) { + len += (size_t)just_read; + if (len >= capacity) + buf = realloc(buf, (capacity *= 2)); + } + return buf; +} + |