Style fixes in TCP code; remove MIN and PAIR from util.h.

[iphydf]

• Moved PAIR to toxav, where it's used (but really this should die).
• Replace most MIN calls with typed min_* calls. Didn't replace the
  ones where the desired semantics are unclear. Moved the MIN macro to
  the one place where it's still used.
• Avoid assignments in while loops. Instead, factored out the loop body
  into a separate bool-returning function.
• Use named types for callbacks (_cb types).
• Avoid assignments in if conditions.
• Removed MAKE_REALLOC and expanded its two calls. We can't have
  templates in C, and this fake templating is ugly and hard to analyse
  and debug (it expands on a single line).
• Moved epoll system include to the .c file, out of the .h file.
• Avoid assignments in expressions (a = b = c;).
• Avoid multiple declarators per struct member declaration.
• Fix naming inconsistencies.
• Replace net_to_host macro with function.

---

This change is 

[sudden6]

Reviewed 17 of 19 files at r1.
Reviewable status: 0 of 1 LGTMs obtained (waiting on @sudden6)

---

toxcore/network.c, line 1384 at r1 (raw file):

    // Used to avoid malloc parameter overflow
    const size_t MAX_COUNT = min_u64(SIZE_MAX, INT32_MAX) / sizeof(IP_Port);

is SIZE_MAX guaranteed to always fit in a uint64_t? If not, at least add a comment.

---

toxcore/TCP_client.c, line 38 at r1 (raw file):

typedef struct TCP_Client_Conn {
    uint8_t status; /* 0 if not used, 1 if other is offline, 2 if other is online. */

Turn this into an enum? If not in this PR maybe add a TODO?

---

toxcore/TCP_server.c, line 55 at r1 (raw file):

    uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE];
    uint32_t index;
    uint8_t status; /* 0 if not used, 1 if other is offline, 2 if other is online. */

enum?

[iphydf]

Reviewable status: 0 of 1 LGTMs obtained (waiting on @sudden6)

---

toxcore/network.c, line 1384 at r1 (raw file):

Previously, sudden6 wrote…

is SIZE_MAX guaranteed to always fit in a uint64_t? If not, at least add a comment.

Yes, the only platform that this would potentially not fit into would be one with 128 bit memory addressing, and toxcore doesn't support any of those. The only architectures that have 128 bit or greater memory addressing are GPUs and even there size_t would be at most 64 bit (the wider bus allows parallelism, not more memory).

---

toxcore/TCP_client.c, line 38 at r1 (raw file):

Previously, sudden6 wrote…

Turn this into an enum? If not in this PR maybe add a TODO?

Done.

---

toxcore/TCP_server.c, line 55 at r1 (raw file):

Previously, sudden6 wrote…

enum?

Done.

[sudden6]

Reviewed 1 of 19 files at r1, 6 of 7 files at r2.
Reviewable status: 0 of 1 LGTMs obtained (waiting on @sudden6)

---

toxcore/network.c, line 1384 at r1 (raw file):

Previously, iphydf wrote…

Yes, the only platform that this would potentially not fit into would be one with 128 bit memory addressing, and toxcore doesn't support any of those. The only architectures that have 128 bit or greater memory addressing are GPUs and even there size_t would be at most 64 bit (the wider bus allows parallelism, not more memory).

To prepare for the future and exotic machines add an assert?

[iphydf]

Reviewable status: 0 of 1 LGTMs obtained (waiting on @sudden6)

---

toxcore/network.c, line 1384 at r1 (raw file):

Previously, sudden6 wrote…

To prepare for the future and exotic machines add an assert?

Done, in monolith_test.c, as static assert.

[sudden6]

Reviewed 1 of 7 files at r2, 4 of 4 files at r3.
Reviewable status: 0 of 1 LGTMs obtained (waiting on @sudden6)

[sudden6]

Reviewable status: complete! 1 of 1 LGTMs obtained