diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/yes.c | 89 |
1 files changed, 38 insertions, 51 deletions
@@ -24,6 +24,7 @@ #include "system.h" #include "error.h" +#include "full-write.h" #include "long-options.h" /* The official name of this program (e.g., no 'g' prefix). */ @@ -58,9 +59,6 @@ Repeatedly output a line with all specified STRING(s), or 'y'.\n\ int main (int argc, char **argv) { - char buf[BUFSIZ]; - char *pbuf = buf; - initialize_main (&argc, &argv); set_program_name (argv[0]); setlocale (LC_ALL, ""); @@ -74,68 +72,57 @@ main (int argc, char **argv) if (getopt_long (argc, argv, "+", NULL, NULL) != -1) usage (EXIT_FAILURE); + char **operands = argv + optind; char **operand_lim = argv + argc; if (optind == argc) *operand_lim++ = bad_cast ("y"); /* Buffer data locally once, rather than having the large overhead of stdio buffering each item. */ - char **operandp; - for (operandp = argv + optind; operandp < operand_lim; operandp++) + size_t bufalloc = 0; + bool reuse_operand_strings = true; + for (char **operandp = operands; operandp < operand_lim; operandp++) { - size_t len = strlen (*operandp); - if (BUFSIZ < len || BUFSIZ - len <= pbuf - buf) - break; - memcpy (pbuf, *operandp, len); - pbuf += len; - *pbuf++ = operandp + 1 == operand_lim ? '\n' : ' '; + size_t operand_len = strlen (*operandp); + bufalloc += operand_len + 1; + if (operandp + 1 < operand_lim + && *operandp + operand_len + 1 != operandp[1]) + reuse_operand_strings = false; } - /* The normal case is to continuously output the local buffer. */ - if (operandp == operand_lim) + /* Improve performance by using a buffer size greater than BUFSIZ / 2. */ + if (bufalloc <= BUFSIZ / 2) { - size_t line_len = pbuf - buf; - size_t lines = BUFSIZ / line_len; - while (--lines) - { - memcpy (pbuf, pbuf - line_len, line_len); - pbuf += line_len; - } + bufalloc = BUFSIZ; + reuse_operand_strings = false; } - while (operandp == operand_lim) + + /* Fill the buffer with one copy of the output. If possible, reuse + the operands strings; this wins when the buffer would be large. */ + char *buf = reuse_operand_strings ? *operands : xmalloc (bufalloc); + size_t bufused = 0; + for (char **operandp = operands; operandp < operand_lim; operandp++) { - char const* pwrite = buf; - size_t to_write = pbuf - buf; - while (to_write) - { - ssize_t written = write (STDOUT_FILENO, pwrite, to_write); - if (written < 0) - { - error (0, errno, _("standard output")); - return EXIT_FAILURE; - } - to_write -= written; - pwrite += written; - } + size_t operand_len = strlen (*operandp); + if (! reuse_operand_strings) + memcpy (buf + bufused, *operandp, operand_len); + bufused += operand_len; + buf[bufused++] = ' '; } + buf[bufused - 1] = '\n'; - /* If the data doesn't fit in BUFSIZ then output - what we've buffered, and iterate over the remaining items. */ - while (true) + /* If a larger buffer was allocated, fill it by repeating the buffer + contents. */ + size_t copysize = bufused; + for (size_t copies = bufalloc / copysize; --copies; ) { - if ((pbuf - buf) && fwrite (buf, pbuf - buf, 1, stdout) != 1) - { - error (0, errno, _("standard output")); - clearerr (stdout); - return EXIT_FAILURE; - } - for (char **trailing = operandp; trailing < operand_lim; trailing++) - if (fputs (*trailing, stdout) == EOF - || putchar (trailing + 1 == operand_lim ? '\n' : ' ') == EOF) - { - error (0, errno, _("standard output")); - clearerr (stdout); - return EXIT_FAILURE; - } + memcpy (buf + bufused, buf, copysize); + bufused += copysize; } + + /* Repeatedly output the buffer until there is a write error; then fail. */ + while (full_write (STDOUT_FILENO, buf, bufused) == bufused) + continue; + error (0, errno, _("standard output")); + return EXIT_FAILURE; } |