ast.js

{ type: 'Program',
  body: 
   [ { type: 'FunctionDeclaration',
       id: { type: 'Identifier', name: 'main' },
       params: [],
       kind: { type: 'Identifier', name: 'int' },
       body: 
        { type: 'BlockStatement',
          body: 
           [ { type: 'VariableStatement',
               declarations: 
                [ { type: 'VariableDeclaration',
                    id: { type: 'Identifier', name: 'path' },
                    kind: null } ],
               init: 
                { type: 'Literal',
                  value: 'logs.json' } },
             { type: 'VariableStatement',
               declarations: 
                [ { type: 'VariableDeclaration',
                    id: { type: 'Identifier', name: 'fp' },
                    kind: { type: 'Identifier', name: 'file' } } ],
               init: 
                { type: 'CallExpression',
                  callee: { type: 'Identifier', name: 'fopen' },
                  args: 
                   [ { type: 'Identifier', name: 'path' },
                     { type: 'Literal', value: 'r' } ] } },
             { type: 'IfStatement',
               test: 
                { type: 'BinaryExpression',
                  operator: '==',
                  left: { type: 'Identifier', name: 'fp' },
                  right: { type: 'Literal', value: null } },
               consequent: 
                { type: 'BlockStatement',
                  body: 
                   [ { type: 'ExpressionStatement',
                       expression: 
                        { type: 'CallExpression',
                          callee: { type: 'Identifier', name: 'printf' },
                          args: 
                           [ { type: 'Literal', value: 'error opening %s' },
                             { type: 'Identifier', name: 'path' } ] } },
                     { type: 'ExpressionStatement',
                       expression: 
                        { type: 'CallExpression',
                          callee: { type: 'Identifier', name: 'exit' },
                          args: [ { type: 'Literal', value: 1 } ] } } ] },
               alternate: null },
             { type: 'VariableStatement',
               declarations: 
                [ { type: 'VariableDeclaration',
                    id: { type: 'Identifier', name: 'line' },
                    kind: { type: 'Identifier', name: 'string' } } ],
               init: { type: 'Literal', value: null } },
             { type: 'VariableStatement',
               declarations: 
                [ { type: 'VariableDeclaration',
                    id: { type: 'Identifier', name: 'len' },
                    kind: { type: 'Identifier', name: 'size_t' } } ],
               init: null },
             { type: 'VariableStatement',
               declarations: 
                [ { type: 'VariableDeclaration',
                    id: { type: 'Identifier', name: 'read' },
                    kind: { type: 'Identifier', name: 'ssize_t' } } ],
               init: null },
             { type: 'VariableStatement',
               declarations: 
                [ { type: 'VariableDeclaration',
                    id: { type: 'Identifier', name: 'total' },
                    kind: { type: 'Identifier', name: 'ssize_t' } } ],
               init: null },
             { type: 'WhileStatement',
               test: { type: 'Literal', value: 1 },
               body: 
                { type: 'BlockStatement',
                  body: 
                   [ { type: 'ExpressionStatement',
                       expression: 
                        { type: 'AssignmentExpression',
                          operator: '=',
                          left: { type: 'Identifier', name: 'read' },
                          right: 
                           { type: 'CallExpression',
                             callee: { type: 'Identifier', name: 'getline' },
                             args: 
                              [ { type: 'Identifier', name: 'line', addr: true },
                                { type: 'Identifier', name: 'len', addr: true },
                                { type: 'Identifier', name: 'fp' } ] } } },
                     { type: 'IfStatement',
                       test: 
                        { type: 'BinaryExpression',
                          operator: '==',
                          left: { type: 'Identifier', name: 'read' },
                          right: 
                           { type: 'UnaryExpression',
                             operator: '-',
                             arg: { type: 'Literal', value: 1 },
                             prefix: true } },
                       consequent: { type: 'BreakStatement', label: null } },
                     { type: 'ExpressionStatement',
                       expression: 
                        { type: 'AssignmentExpression',
                          operator: '+=',
                          left: { type: 'Identifier', name: 'total' },
                          right: { type: 'Identifier', name: 'read' } } },
                     { type: 'ExpressionStatement',
                       expression: 
                        { type: 'CallExpression',
                          callee: { type: 'Identifier', name: 'printf' },
                          args: 
                           [ { type: 'Literal', value: '\r  %zd' },
                             { type: 'Identifier', name: 'total' } ] } } ] } },
             { type: 'ReturnStatement', arg: { type: 'Literal', value: 0 } } ] } } ] }

main.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

int
main () {
  FILE * fp = fopen("logs.json", "r");
  
  if (fp == NULL) {
    printf("error opening %s", path);
    exit(1);
  }

  char * line = NULL;
  size_t len;
  ssize_t read;
  ssize_t total;

  while (1) {
    read = getline(&line, &len, fp);
    if (read == -1) break;
    total += read;
    printf("\r  %zd", total);
  }
  
  return 0;
}

main.rs

fn main() int {
  let fp file = fopen("logs.json", "r")

  if fp == null {
    printf("error opening %s", path)
    exit(1)
  }

  let line string = null
  let len size_t
  let read ssize_t
  let total ssize_t

  for {
    read = getline(&line, &len, fp)
    break if read == -1
    total += read
    printf("\r  %zd", total)
  }

  return 0
}