https://github.com/ostreedev/ostree/pull/2293

testurichars.c

#include <stdio.h>

/* copied from libsoup */
/* 00 URI_UNRESERVED
 * 01 URI_PCT_ENCODED
 * 02 URI_GEN_DELIMS
 * 04 URI_SUB_DELIMS
 * 08 HTTP_SEPARATOR
 * 10 HTTP_CTL
 */
const char soup_char_attributes[] = {
	/* 0x00 - 0x07 */
	0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
	/* 0x08 - 0x0f */
	0x11, 0x19, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
	/* 0x10 - 0x17 */
	0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
	/* 0x18 - 0x1f */
	0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
	/*  !"#$%&' */
	0x09, 0x04, 0x09, 0x02, 0x04, 0x01, 0x04, 0x04,
	/* ()*+,-./ */
	0x0c, 0x0c, 0x04, 0x04, 0x0c, 0x00, 0x00, 0x0a,
	/* 01234567 */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* 89:;<=>? */
	0x00, 0x00, 0x0a, 0x0c, 0x09, 0x0a, 0x09, 0x0a,
	/* @ABCDEFG */
	0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* HIJKLMNO */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* PQRSTUVW */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* XYZ[\]^_ */
	0x00, 0x00, 0x00, 0x0a, 0x09, 0x0a, 0x01, 0x00,
	/* `abcdefg */
	0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* hijklmno */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* pqrstuvw */
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	/* xyz{|}~  */
	0x00, 0x00, 0x00, 0x09, 0x01, 0x09, 0x00, 0x11,
	/* 0x80 - 0xFF */
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
	0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
};

/* copied from GLib */
static const char acceptable[96] = {
  /* A table of the ASCII chars from space (32) to DEL (127) */
  /*      !    "    #    $    %    &    '    (    )    *    +    ,    -    .    / */ 
  0x00,0x3F,0x20,0x20,0x28,0x00,0x2C,0x3F,0x3F,0x3F,0x3F,0x2A,0x28,0x3F,0x3F,0x1C,
  /* 0    1    2    3    4    5    6    7    8    9    :    ;    <    =    >    ? */
  0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x38,0x20,0x20,0x2C,0x20,0x20,
  /* @    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O */
  0x38,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,
  /* P    Q    R    S    T    U    V    W    X    Y    Z    [    \    ]    ^    _ */
  0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x20,0x20,0x20,0x20,0x3F,
  /* `    a    b    c    d    e    f    g    h    i    j    k    l    m    n    o */
  0x20,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,
  /* p    q    r    s    t    u    v    w    x    y    z    {    |    }    ~  DEL */
  0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x20,0x20,0x20,0x3F,0x20
};

#define ACCEPTABLE(a) ((a)>=32 && (a)<128 && (acceptable[(a)-32] & 0x8))

int main(int argc, char **argv) {
for (int i = 0; i <= 0xFF; i++) {
  if ((soup_char_attributes[i] & 0x07)) {
    if (ACCEPTABLE(i))
      continue;
    if (i >= 0x20 && i <= 0x7E)
      printf ("%#02X %c\n", i, (char)i);
    else
      printf ("%#02X\n", i);
  }
}
return 0;
}