Private string embedded inside C code.


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# 1  
Private string embedded inside C code.

Private string inside C code.
After a lot of messing around, time consumption and jiggery-pokery I finally got a common piece of code for this thread working:

Embed text in C code

The OP wanted the string to be alone and as close to the top of the code as possible and not inside the data section.
Well, I wanted to make it possible for AMIGA users to have the same as we UNIX users, and upload to AMINET to suit.
But when it compiled in gcc 2.95.3 i got some warnings and errors, etc... When the warnings and errors went the test code similar to the URL above inverted everything and the data section was at the top and the private string was below the data section. After much thought this was the demo code that worked for the platforms tested on.

The assembly code does not need to be changed at all as the 2 instructions are the same for both architectures.

Code:
/* embed_private_string.c */
/* Guaranteed to allow up to 120 ASCII characters inside a function using gcc. */
/* It IS easily possible to get many, many more characters but this is a minimal approach. */
/* Without any modifications this will compile on these platforms:- */
/* Works on gcc 2.95.3 for the classic AMIGA OS 3.0.x using ADE the *NIX emulator, Motorola 68000+ architecture. */
/* Works on gcc 4.2.1 for OSX 10.14.x, 64 bit, Intel architecture. */
/* Works on gcc 7.3.0 for Linux Mint 19, 64 bit, Intel architecture. */
/* -- I have no idea whether this compiles on the current gcc 8.2.0, 20-02-2019. -- */

#include <stdio.h>

void Private_String(void)
{
    /* To keep this string near the top of the code this must be the first function. */
    /* This string will always be separate from the normal data section. */
    /* It MUST be an EVEN number of characters long, including a single */
    /* newline and the required NULL padding characters at the end. */
    asm("    jmp    exit_asm;"
    "string:"
    "    .asciz    \"'$VER (C)_Barry_Walker_CC0_Licence_[PD].'\\n\\0\";"
    "exit_asm:"
    "    nop;");
    /* IMPORTANT! DO NOT use the assembler RETURN instruction at all! */
    return;
}

/* All further strings will be stored in the data section area. */
void Test_Function(void)
{
    /* This function is just a test function. */
    printf("\nA test function to check that the strings are in the data section.\n"); 
    return;
}

int main(void)
{
    /* Note: Private_String() does absolutely NOTHING. */
    Private_String();
    Test_Function();
    printf("\nThese strings should be in the data section.\n");
    printf("The hidden string is inside the code section.\n");
    printf("'$VER (C)_Barry_Walker_CC0_Licence_[PD].'\n\n");
    return 0;
}

Results for OSX 10.14.x:
Code:
00000e00  55 48 89 e5 e9 2c 00 00  00 27 24 56 45 52 20 28  |UH...,...'$VER (|
00000e10  43 29 5f 42 61 72 72 79  5f 57 61 6c 6b 65 72 5f  |C)_Barry_Walker_|
00000e20  43 43 30 5f 4c 69 63 65  6e 63 65 5f 5b 50 44 5d  |CC0_Licence_[PD]|
00000e30  2e 27 0a 00 00 90 5d c3  0f 1f 84 00 00 00 00 00  |.'....].........|
00000e40  55 48 89 e5 48 83 ec 10  48 8d 3d 87 00 00 00 b0  |UH..H...H.=.....|
00000e50  00 e8 60 00 00 00 89 45  fc 48 83 c4 10 5d c3 90  |..`....E.H...]..|
00000e60  55 48 89 e5 48 83 ec 10  c7 45 fc 00 00 00 00 e8  |UH..H....E......|
00000e70  8c ff ff ff e8 c7 ff ff  ff 48 8d 3d 9b 00 00 00  |.........H.=....|
00000e80  b0 00 e8 2f 00 00 00 48  8d 3d bc 00 00 00 89 45  |.../...H.=.....E|
00000e90  f8 b0 00 e8 1e 00 00 00  48 8d 3d da 00 00 00 89  |........H.=.....|
00000ea0  45 f4 b0 00 e8 0d 00 00  00 31 c9 89 45 f0 89 c8  |E........1..E...|
00000eb0  48 83 c4 10 5d c3 ff 25  54 01 00 00 4c 8d 1d 45  |H...]..%T...L..E|
00000ec0  01 00 00 41 53 ff 25 35  01 00 00 90 68 00 00 00  |...AS.%5....h...|
00000ed0  00 e9 e6 ff ff ff 0a 41  20 74 65 73 74 20 66 75  |.......A test fu|
00000ee0  6e 63 74 69 6f 6e 20 74  6f 20 63 68 65 63 6b 20  |nction to check |
00000ef0  74 68 61 74 20 74 68 65  20 73 74 72 69 6e 67 73  |that the strings|
00000f00  20 61 72 65 20 69 6e 20  74 68 65 20 64 61 74 61  | are in the data|
00000f10  20 73 65 63 74 69 6f 6e  2e 0a 00 0a 54 68 65 73  | section....Thes|
00000f20  65 20 73 74 72 69 6e 67  73 20 73 68 6f 75 6c 64  |e strings should|
00000f30  20 62 65 20 69 6e 20 74  68 65 20 64 61 74 61 20  | be in the data |
00000f40  73 65 63 74 69 6f 6e 2e  0a 00 54 68 65 20 68 69  |section...The hi|
00000f50  64 64 65 6e 20 73 74 72  69 6e 67 20 69 73 20 69  |dden string is i|
00000f60  6e 73 69 64 65 20 74 68  65 20 63 6f 64 65 20 73  |nside the code s|
00000f70  65 63 74 69 6f 6e 2e 0a  00 27 24 56 45 52 20 28  |ection...'$VER (|

It looks much the same on all three OSes even though it was originally inverted on the AMIGA A1200.

It took wime to get it working, but this might be a better bet for drew77 as it is consistent on differing platforms and compiles on differing versions of gcc.

Have fun...

EDIT:
Off to give this to the AMINET site soon...

Last edited by wisecracker; 02-20-2019 at 01:07 PM.. Reason: See above...
These 2 Users Gave Thanks to wisecracker For This Post:
# 2  
As a grand finale to this and the other thread, this I never realised; comments, jokes, passing remarks and function characteristics inside any and every function inside the executable itself.

I knew that the idea would work but not to this extent...
Code:
/* embed_private_string.c */
/* Guaranteed to allow up to 120 ASCII characters inside a function using gcc. */
/* It IS easily possible to get many, many more characters but this is a minimal approach. */
/* Without any modifications this will compile on these platforms:- */
/* Works on gcc 2.95.3 for the classic AMIGA OS 3.0.x using ADE the *NIX emulator, Motorola 68000+ architecture. */
/* Works on gcc 4.2.1 for OSX 10.14.x, 64 bit, Intel architecture. */
/* Works on gcc 7.3.0 for Linux Mint 19, 64 bit, Intel architecture. */
/* -- I have no idea whether this compiles on the current gcc 8.2.0, 20-02-2019. -- */

#include <stdio.h>

void Private_String(void)
{
    /* To keep this string near the top of the code this must be the first function. */
    /* This string will always be separate from the normal data section. */
    /* It MUST be an EVEN number of characters long, including a */
    /* single newline and the required NULL characters at the end. */
    asm("    jmp    exit_asm1;"
    "string1:"
    "    .asciz    \"'$VER (C)_Barry_Walker_CC0_Licence_[PD].'\\n\\0\";"
    "exit_asm1:"
    "    nop;");
    /* IMPORTANT! DO NOT use the assembler RETURN instruction at all! */
    return;
}

void Test_Function(void)
{
    /* The comment will be inside the function code, all other strings will be in the data section. */
    asm("    jmp    exit_asm2;"
    "string2:"
    "    .asciz    \"'This is the Test_Function().'\\n\";"
    "exit_asm2:"
    "    nop;");
    /* This function is just a test function. */
    printf("\nA test function to check that the strings are in the data section.\n"); 
    return;
}

int main(void)
{
    /* The comment will be inside the function code, all other strings will be in the data section. */
    asm("    jmp    exit_asm3;"
    "string3:"
    "    .asciz    \"'This I never expected, comments inside the code section!'\\n\";"
    "exit_asm3:"
    "    nop;");
    /* Note: Private_String() does absolutely NOTHING. */
    Private_String();
    Test_Function();
    printf("\nThese strings should be in the data section.\n");
    printf("The hidden string is inside the code section.\n");
    printf("'$VER (C)_Barry_Walker_CC0_Licence_[PD].'\n\n");
    return 0;
}

/* ***************************************************************************

00000d80  55 48 89 e5 e9 2c 00 00  00 27 24 56 45 52 20 28  |UH...,...'$VER (|
00000d90  43 29 5f 42 61 72 72 79  5f 57 61 6c 6b 65 72 5f  |C)_Barry_Walker_|
00000da0  43 43 30 5f 4c 69 63 65  6e 63 65 5f 5b 50 44 5d  |CC0_Licence_[PD]|
00000db0  2e 27 0a 00 00 90 5d c3  0f 1f 84 00 00 00 00 00  |.'....].........|
00000dc0  55 48 89 e5 48 83 ec 10  e9 20 00 00 00 27 54 68  |UH..H.... ...'Th|
00000dd0  69 73 20 69 73 20 74 68  65 20 54 65 73 74 5f 46  |is is the Test_F|
00000de0  75 6e 63 74 69 6f 6e 28  29 2e 27 0a 00 90 48 8d  |unction().'...H.|
00000df0  3d d5 00 00 00 b0 00 e8  ac 00 00 00 89 45 fc 48  |=............E.H|
00000e00  83 c4 10 5d c3 66 66 2e  0f 1f 84 00 00 00 00 00  |...].ff.........|
00000e10  55 48 89 e5 48 83 ec 10  c7 45 fc 00 00 00 00 e9  |UH..H....E......|
00000e20  3c 00 00 00 27 54 68 69  73 20 49 20 6e 65 76 65  |<...'This I neve|
00000e30  72 20 65 78 70 65 63 74  65 64 2c 20 63 6f 6d 6d  |r expected, comm|
00000e40  65 6e 74 73 20 69 6e 73  69 64 65 20 74 68 65 20  |ents inside the |
00000e50  63 6f 64 65 20 73 65 63  74 69 6f 6e 21 27 0a 00  |code section!'..|
00000e60  90 e8 1a ff ff ff e8 55  ff ff ff 48 8d 3d 9d 00  |.......U...H.=..|
00000e70  00 00 b0 00 e8 2f 00 00  00 48 8d 3d be 00 00 00  |...../...H.=....|
00000e80  89 45 f8 b0 00 e8 1e 00  00 00 48 8d 3d dc 00 00  |.E........H.=...|
00000e90  00 89 45 f4 b0 00 e8 0d  00 00 00 31 c9 89 45 f0  |..E........1..E.|
00000ea0  89 c8 48 83 c4 10 5d c3  ff 25 62 01 00 00 00 00  |..H...]..%b.....|
00000eb0  4c 8d 1d 51 01 00 00 41  53 ff 25 41 01 00 00 90  |L..Q...AS.%A....|
00000ec0  68 00 00 00 00 e9 e6 ff  ff ff 0a 41 20 74 65 73  |h..........A tes|
00000ed0  74 20 66 75 6e 63 74 69  6f 6e 20 74 6f 20 63 68  |t function to ch|
00000ee0  65 63 6b 20 74 68 61 74  20 74 68 65 20 73 74 72  |eck that the str|
00000ef0  69 6e 67 73 20 61 72 65  20 69 6e 20 74 68 65 20  |ings are in the |
00000f00  64 61 74 61 20 73 65 63  74 69 6f 6e 2e 0a 00 0a  |data section....|
00000f10  54 68 65 73 65 20 73 74  72 69 6e 67 73 20 73 68  |These strings sh|
00000f20  6f 75 6c 64 20 62 65 20  69 6e 20 74 68 65 20 64  |ould be in the d|
00000f30  61 74 61 20 73 65 63 74  69 6f 6e 2e 0a 00 54 68  |ata section...Th|
00000f40  65 20 68 69 64 64 65 6e  20 73 74 72 69 6e 67 20  |e hidden string |
00000f50  69 73 20 69 6e 73 69 64  65 20 74 68 65 20 63 6f  |is inside the co|
00000f60  64 65 20 73 65 63 74 69  6f 6e 2e 0a 00 27 24 56  |de section...'$V|
00000f70  45 52 20 28 43 29 5f 42  61 72 72 79 5f 57 61 6c  |ER (C)_Barry_Wal|
00000f80  6b 65 72 5f 43 43 30 5f  4c 69 63 65 6e 63 65 5f  |ker_CC0_Licence_|
00000f90  5b 50 44 5d 2e 27 0a 0a  00 00 00 00 01 00 00 00  |[PD].'..........|

 *************************************************************************** */

Code:
Last login: Thu Feb 21 13:38:22 on ttys000
AMIGA:amiga~> cd Desktop/Code/C
AMIGA:amiga~/Desktop/Code/C> gcc embed_asm.c
AMIGA:amiga~/Desktop/Code/C> ./a.out

A test function to check that the strings are in the data section.

These strings should be in the data section.
The hidden string is inside the code section.
'$VER (C)_Barry_Walker_CC0_Licence_[PD].'

AMIGA:amiga~/Desktop/Code/C> _

I consider this finalised now...
This User Gave Thanks to wisecracker For This Post:
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