From mboxrd@z Thu Jan 1 00:00:00 1970 From: john at keeping.me.uk (John Keeping) Date: Sat, 16 Jun 2018 14:07:29 +0100 Subject: [PATCH 2/2] shared: use strbuf for expanding macros In-Reply-To: References: <20180616130448.GO1922@john.keeping.me.uk> Message-ID: <557cc424e8607a045d2ffdbca94c35c11caaa1d7.1529154091.git.john@keeping.me.uk> Avoid a fixed size buffer by using struct strbuf to build the expanded value. Signed-off-by: John Keeping --- shared.c | 73 +++++++++++++++++++++----------------------------------- 1 file changed, 27 insertions(+), 46 deletions(-) diff --git a/shared.c b/shared.c index 32d0f46..6ce3990 100644 --- a/shared.c +++ b/shared.c @@ -467,69 +467,50 @@ static int is_token_char(char c) return isalnum(c) || c == '_'; } -/* Replace name with getenv(name), return pointer to zero-terminating char +/* Replace name with getenv(name). */ -static char *expand_macro(char *name, int maxlength) +static void expand_macro(struct strbuf *buf, ssize_t start) { - char *value; - int len; + const char *name = buf->buf + start; + const char *value = getenv(name); - len = 0; - value = getenv(name); - if (value) { - len = strlen(value); - if (len > maxlength) - len = maxlength; - strncpy(name, value, len); - } - return name + len; + /* Truncate output to remove variable name. */ + strbuf_setlen(buf, start); + + if (value) + strbuf_addstr(buf, value); } -#define EXPBUFSIZE (1024 * 8) - /* Replace all tokens prefixed by '$' in the specified text with the * value of the named environment variable. * NB: the return value is allocated, it must be freed by the caller. */ char *expand_macros(const char *txt) { - static char result[EXPBUFSIZE]; - char *p, *start; - int len; + struct strbuf result = STRBUF_INIT; + ssize_t start = -1; - p = result; - start = NULL; - while (p < result + EXPBUFSIZE - 1 && txt && *txt) { - *p = *txt; - if (start) { + while (txt && *txt) { + if (start >= 0) { if (!is_token_char(*txt)) { - if (p - start > 0) { - *p = '\0'; - len = result + EXPBUFSIZE - start - 1; - p = expand_macro(start, len) - 1; - } - start = NULL; - txt--; + if (result.len - start >= 0) + expand_macro(&result, start); + start = -1; } - p++; - txt++; - continue; } - if (*txt == '$') { - start = p; - txt++; - continue; - } - p++; + + if (*txt == '$') + start = result.len; + else + strbuf_addch(&result, *txt); + txt++; } - *p = '\0'; - if (start && p - start > 0) { - len = result + EXPBUFSIZE - start - 1; - p = expand_macro(start, len); - *p = '\0'; - } - return xstrdup(result); + + if (start >= 0 && result.len - start > 0) + expand_macro(&result, start); + + return strbuf_detach(&result, NULL); } char *get_mimetype_for_filename(const char *filename) -- 2.17.1