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      1 /* printf.c - Format and Print the data.
      2  *
      3  * Copyright 2014 Sandeep Sharma <sandeep.jack2756 (at) gmail.com>
      4  * Copyright 2014 Kyungwan Han <asura321 (at) gmail.com>
      5  *
      6  * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html
      7  *
      8  * todo: *m$ ala printf("%1$d:%2$.*3$d:%4$.*3$d\n", hour, min, precision, sec);
      9 
     10 USE_PRINTF(NEWTOY(printf, "<1?^", TOYFLAG_USR|TOYFLAG_BIN))
     11 
     12 config PRINTF
     13   bool "printf"
     14   default y
     15   help
     16     usage: printf FORMAT [ARGUMENT...]
     17 
     18     Format and print ARGUMENT(s) according to FORMAT, using C printf syntax
     19     (% escapes for cdeEfgGiosuxX, \ escapes for abefnrtv0 or \OCTAL or \xHEX).
     20 */
     21 
     22 #define FOR_printf
     23 #include "toys.h"
     24 
     25 // Detect matching character (return true/false) and advance pointer if match.
     26 static int eat(char **s, char c)
     27 {
     28   int x = (**s == c);
     29 
     30   if (x) ++*s;
     31 
     32   return x;
     33 }
     34 
     35 // Parse escape sequences.
     36 static int handle_slash(char **esc_val, int posix)
     37 {
     38   char *ptr = *esc_val;
     39   int len, base = 0;
     40   unsigned result = 0, num;
     41 
     42   if (*ptr == 'c') xexit();
     43 
     44   // 0x12 hex escapes have 1-2 digits, \123 octal escapes have 1-3 digits.
     45   if (eat(&ptr, 'x')) base = 16;
     46   else {
     47     if (posix && *ptr=='0') ptr++;
     48     if (*ptr >= '0' && *ptr <= '7') base = 8;
     49   }
     50   len = (char []){0,3,2}[base/8];
     51 
     52   // Not a hex or octal escape? (This catches trailing \)
     53   if (!len) {
     54     if (!(result = unescape(*ptr))) result = '\\';
     55     else ++*esc_val;
     56 
     57     return result;
     58   }
     59 
     60   while (len) {
     61     num = tolower(*ptr) - '0';
     62     if (num >= 'a'-'0') num += '0'-'a'+10;
     63     if (num >= base) {
     64       // Don't parse invalid hex value ala "\xvd", print it verbatim
     65       if (base == 16 && len == 2) {
     66         ptr--;
     67         result = '\\';
     68       }
     69       break;
     70     }
     71     result = (result*base)+num;
     72     ptr++;
     73     len--;
     74   }
     75   *esc_val = ptr;
     76 
     77   return result;
     78 }
     79 
     80 void printf_main(void)
     81 {
     82   char **arg = toys.optargs+1;
     83 
     84   // Repeat format until arguments consumed
     85   for (;;) {
     86     int seen = 0;
     87     char *f = *toys.optargs;
     88 
     89     // Loop through characters in format
     90     while (*f) {
     91       if (eat(&f, '\\')) putchar(handle_slash(&f, 0));
     92       else if (!eat(&f, '%') || *f == '%') putchar(*f++);
     93 
     94       // Handle %escape
     95       else {
     96         char c, *end = 0, *aa, *to = toybuf;
     97         int wp[] = {0,-1}, i = 0;
     98 
     99         // Parse width.precision between % and type indicator.
    100         *to++ = '%';
    101         while (strchr("-+# '0", *f) && (to-toybuf)<10) *to++ = *f++;
    102         for (;;) {
    103           if (eat(&f, '*')) {
    104             if (*arg) wp[i] = atolx(*arg++);
    105           } else while (*f >= '0' && *f <= '9') wp[i] = (wp[i]*10)+(*f++)-'0';
    106           if (i++ || !eat(&f, '.')) break;
    107           wp[1] = 0;
    108         }
    109         c = *f++;
    110         seen = sprintf(to, "*.*%c", c);;
    111         errno = 0;
    112         aa = *arg ? *arg++ : "";
    113 
    114         // Output %esc using parsed format string
    115         if (c == 'b') {
    116           while (*aa) putchar(eat(&aa, '\\') ? handle_slash(&aa, 1) : *aa++);
    117 
    118           continue;
    119         } else if (c == 'c') printf(toybuf, wp[0], wp[1], *aa);
    120         else if (c == 's') printf(toybuf, wp[0], wp[1], aa);
    121         else if (strchr("diouxX", c)) {
    122           long long ll;
    123 
    124           if (*aa == '\'' || *aa == '"') ll = aa[1];
    125           else ll = strtoll(aa, &end, 0);
    126 
    127           sprintf(to, "*.*ll%c", c);
    128           printf(toybuf, wp[0], wp[1], ll);
    129         } else if (strchr("feEgG", c)) {
    130           long double ld = strtold(aa, &end);
    131 
    132           sprintf(to, "*.*L%c", c);
    133           printf(toybuf, wp[0], wp[1], ld);
    134         } else error_exit("bad %%%c@%ld", c, (long)(f-*toys.optargs));
    135 
    136         if (end && (errno || *end)) perror_msg("bad %%%c %s", c, aa);
    137       }
    138     }
    139 
    140     // Posix says to keep looping through format until we consume all args.
    141     // This only works if the format actually consumed at least one arg.
    142     if (!seen || !*arg) break;
    143   }
    144 }
    145