external/ibm-public/postfix/dist/src/util/readlline.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      readlline 3
   6 /* SUMMARY
   7 /*      read logical line
   8 /* SYNOPSIS
   9 /*      #include <readlline.h>
  10 /*
  11 /*      VSTRING *readlline(buf, fp, lineno)
  12 /*      VSTRING *buf;
  13 /*      VSTREAM *fp;
  14 /*      int     *lineno;
  15 /* DESCRIPTION
  16 /*      readlline() reads one logical line from the named stream.
  17 /* .IP "blank lines and comments"
  18 /*      Empty lines and whitespace-only lines are ignored, as
  19 /*      are lines whose first non-whitespace character is a `#'.
  20 /* .IP "multi-line text"
  21 /*      A logical line starts with non-whitespace text. A line that
  22 /*      starts with whitespace continues a logical line.
  23 /* .PP
  24 /*      The result value is the input buffer argument or a null pointer
  25 /*      when no input is found.
  26 /*
  27 /*      Arguments:
  28 /* .IP buf
  29 /*      A variable-length buffer for input. The result is null terminated.
  30 /* .IP fp
  31 /*      Handle to an open stream.
  32 /* .IP lineno
  33 /*      A null pointer, or a pointer to an integer that is incremented
  34 /*      after reading a newline character.
  35 /* .RE
  36 /* DIAGNOSTICS
  37 /*      Warning: a continuation line that does not continue preceding text.
  38 /*      The invalid input is ignored, to avoid complicating caller code.
  39 /* SECURITY
  40 /* .ad
  41 /* .fi
  42 /*      readlline() imposes no logical line length limit therefore it
  43 /*      should be used for reading trusted information only.
  44 /* LICENSE
  45 /* .ad
  46 /* .fi
  47 /*      The Secure Mailer license must be distributed with this software.
  48 /* AUTHOR(S)
  49 /*      Wietse Venema
  50 /*      IBM T.J. Watson Research
  51 /*      P.O. Box 704
  52 /*      Yorktown Heights, NY 10598, USA
  53 /*--*/
  54
  55 /* System library. */
  56
  57 #include <sys_defs.h>
  58 #include <ctype.h>
  59
  60 /* Utility library. */
  61
  62 #include "msg.h"
  63 #include "vstream.h"
  64 #include "vstring.h"
  65 #include "readlline.h"
  66
  67 #define STR(x) vstring_str(x)
  68 #define LEN(x) VSTRING_LEN(x)
  69 #define END(x) vstring_end(x)
  70
  71 /* readlline - read one logical line */
  72
  73 VSTRING *readlline(VSTRING *buf, VSTREAM *fp, int *lineno)
  74 {
  75     int     ch;
  76     int     next;
  77     ssize_t start;
  78     char   *cp;
  79
  80     VSTRING_RESET(buf);
  81
  82     /*
  83      * Ignore comment lines, all whitespace lines, and empty lines. Terminate
  84      * at EOF or at the beginning of the next logical line.
  85      */
  86     for (;;) {
  87         /* Read one line, possibly not newline terminated. */
  88         start = LEN(buf);
  89         while ((ch = VSTREAM_GETC(fp)) != VSTREAM_EOF && ch != '\n')
  90             VSTRING_ADDCH(buf, ch);
  91         if (ch == '\n' && lineno != 0)
  92             *lineno += 1;
  93         /* Ignore comment line, all whitespace line, or empty line. */
  94         for (cp = STR(buf) + start; cp < END(buf) && ISSPACE(*cp); cp++)
  95              /* void */ ;
  96         if (cp == END(buf) || *cp == '#')
  97             vstring_truncate(buf, start);
  98         /* Terminate at EOF or at the beginning of the next logical line. */
  99         if (ch == VSTREAM_EOF)
 100             break;
 101         if (LEN(buf) > 0) {
 102             if ((next = VSTREAM_GETC(fp)) != VSTREAM_EOF)
 103                 vstream_ungetc(fp, next);
 104             if (next != '#' && !ISSPACE(next))
 105                 break;
 106         }
 107     }
 108     VSTRING_TERMINATE(buf);
 109
 110     /*
 111      * Invalid input: continuing text without preceding text. Allowing this
 112      * would complicate "postconf -e", which implements its own multi-line
 113      * parsing routine. Do not abort, just warn, so that critical programs
 114      * like postmap do not leave behind a truncated table.
 115      */
 116     if (LEN(buf) > 0 && ISSPACE(*STR(buf))) {
 117         msg_warn("%s: logical line must not start with whitespace: \"%.30s%s\"",
 118                  VSTREAM_PATH(fp), STR(buf),
 119                  LEN(buf) > 30 ? "..." : "");
 120         return (readlline(buf, fp, lineno));
 121     }
 122
 123     /*
 124      * Done.
 125      */
 126     return (LEN(buf) > 0 ? buf : 0);
 127 }