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Annotation of researchv9/sys/boot/stand/readfile.c, revision 1.1.1.2

1.1       root        1: /*
                      2:  * @(#)readfile.c 1.1 86/02/03 Copyright (c) 1985 by Sun Microsystems, Inc.
                      3:  */
                      4: #include <a.out.h>
                      5: 
                      6: /*
                      7:  * Read in a Unix executable file and return its entry point.
                      8:  * Handle the various a.out formats correctly.
                      9:  * "Io" is the standalone file descriptor to read from.
                     10:  * Print informative little messages if "print" is on.
                     11:  * Returns -1 for errors.
                     12:  *
                     13:  * The parameter <LOAD> must be set in the command line to cc, e.g.
                     14:  *     cc -DLOAD=0x4000 -o readfile.c
                     15:  * The makefile takes care of this.
                     16:  */
                     17: int (*
                     18: readfile(io, print))()
                     19:        register int io;
                     20:        int print;
                     21: {
                     22:        struct exec x;
                     23:        register int i;
                     24:        register char *addr;
                     25:        register int shared = 0;
                     26:        register int loadaddr;
                     27:        register int segsiz;
                     28:        register int datasize;
                     29: 
                     30:        i = read(io, (char *)&x, sizeof x);
                     31:        if (x.a_magic == ZMAGIC || x.a_magic == NMAGIC)
                     32:                shared = 1;
                     33:        if (i != sizeof x || (!shared && x.a_magic != OMAGIC)) {
                     34:                printf("Not executable\n");
                     35:                return (int (*)()) -1;
                     36:        }
                     37:        if (print)
                     38:                printf("Size: %d", x.a_text);
                     39:        datasize = x.a_data;
                     40:        if (!shared) {
                     41:                x.a_text = x.a_text + x.a_data;
                     42:                x.a_data = 0;
                     43:        }
                     44:        if (lseek(io, N_TXTOFF(x), 0) == -1)
                     45:                goto shread;
                     46:        if (read(io, (char *)LOAD, (int)x.a_text) < x.a_text)
                     47:                goto shread;
                     48:        addr = (char *)(x.a_text + LOAD);
1.1.1.2 ! root       49:         segsiz = SEGSIZ;
1.1       root       50:        if (shared)
                     51:                while ((int)addr & (segsiz-1))
                     52:                        *addr++ = 0;
                     53:        if (print)
                     54:                printf("+%d", datasize);
                     55:        if (read(io, addr, (int)x.a_data) < x.a_data)
                     56:                goto shread;
                     57:        close(io);              /* Done with it. */
                     58:        if (print)
                     59:                printf("+%d", x.a_bss);
                     60:        addr += x.a_data;
                     61:        for (i = 0; i < x.a_bss; i++)
                     62:                *addr++ = 0;
                     63:        if (print)
                     64:                printf(" bytes\n");
1.1.1.2 ! root       65:        loadaddr = LOAD;
1.1       root       66:        return (int (*)()) (loadaddr);
                     67: 
                     68: shread:
                     69:        printf("Truncated file\n");
                     70:        return (int (*)()) -1;
                     71: }

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