/usr/share/doc/flex/examples/manual/string1.lex is in flex 2.6.4-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 | /*
* string1.lex: Handling strings by using input()
*/
%{
#include <ctype.h>
#include <malloc.h>
#define ALLOC_SIZE 32 /* for (re)allocating the buffer */
#define isodigit(x) ((x) >= '0' && (x) <= '7')
#define hextoint(x) (isdigit((x)) ? (x) - '0' : ((x) - 'A') + 10)
void yyerror(char *message)
{
printf("\nError: %s\n",message);
}
%}
%%
\" {
int inch,count,max_size;
char *buffer;
int temp;
buffer = malloc(ALLOC_SIZE);
max_size = ALLOC_SIZE;
inch = input();
count = 0;
while(inch != EOF && inch != '"' && inch != '\n'){
if(inch == '\\'){
inch = input();
switch(inch){
case '\n': inch = input(); break;
case 'b' : inch = '\b'; break;
case 't' : inch = '\t'; break;
case 'n' : inch = '\n'; break;
case 'v' : inch = '\v'; break;
case 'f' : inch = '\f'; break;
case 'r' : inch = '\r'; break;
case 'X' :
case 'x' : inch = input();
if(isxdigit(inch)){
temp = hextoint(toupper(inch));
inch = input();
if(isxdigit(inch)){
temp = (temp << 4) + hextoint(toupper(inch));
} else {
unput(inch);
}
inch = temp;
} else {
unput(inch);
inch = 'x';
}
break;
default:
if(isodigit(inch)){
temp = inch - '0';
inch = input();
if(isodigit(inch)){
temp = (temp << 3) + (inch - '0');
} else {
unput(inch);
goto done;
}
inch = input();
if(isodigit(inch)){
temp = (temp << 3) + (inch - '0');
} else {
unput(inch);
}
done:
inch = temp;
}
}
}
buffer[count++] = inch;
if(count >= max_size){
buffer = realloc(buffer,max_size + ALLOC_SIZE);
max_size += ALLOC_SIZE;
}
inch = input();
}
if(inch == EOF || inch == '\n'){
yyerror("Unterminated string.");
}
buffer[count] = '\0';
printf("String = \"%s\"\n",buffer);
free(buffer);
}
.
\n
%%
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