ref: 3cf63ee15fce37647fb3e5ce3d757b7cdaf5e872
dir: /sys/src/libstdio/freopen.c/
/* * pANS stdio -- freopen */ #include "iolib.h" /* * Open the named file with the given mode, using the given FILE * Legal modes are given below, `additional characters may follow these sequences': * r rb open to read * w wb open to write, truncating * a ab open to write positioned at eof, creating if non-existant * r+ r+b rb+ open to read and write, creating if non-existant * w+ w+b wb+ open to read and write, truncating * a+ a+b ab+ open to read and write, positioned at eof, creating if non-existant. */ FILE *freopen(const char *name, const char *mode, FILE *f){ int m; if(f->state!=CLOSED){ fclose(f); /* premature; fall through and see what happens */ /* f->state=OPEN; */ } m = *mode++; if(m == 0) return NULL; if(*mode == 'b') mode++; switch(m){ default: return NULL; case 'r': f->fd=open(name, (*mode == '+'? ORDWR: OREAD)); break; case 'w': f->fd=create(name, (*mode == '+'? ORDWR: OWRITE), 0666); break; case 'a': m = (*mode == '+'? ORDWR: OWRITE); f->fd=open(name, m); if(f->fd<0) f->fd=create(name, m, 0666); seek(f->fd, 0LL, 2); break; } if(f->fd==-1) return NULL; f->flags=(mode[0]=='a')? APPEND : 0; f->state=OPEN; f->buf=0; f->rp=0; f->wp=0; f->lp=0; return f; }